Cancer in Nunavut: 1999-2011 · Cancer in Nunavut: 1999-2011 5 Dietary patterns in Nunavut have...

Cancer in Nunavut: 1999-2011

Cancer in Nunavut: 1999-2011

Prepared By:

Population Health Information Department of Health

Government of Nunavut P.O. Box 1000, Station 1033

Iqaluit, NU X0A 0H0 [email protected]

Fall, 2014

2

Table of Contents

Executive summary………………………………………………………….. 3

Background: Nunavut cancer risk factors………………………….. 4

Cancer overview………………………………………………………………. 6

Specific cancer information

Lung and bronchus cancer……………………………………… 7

Digestive system……………………………………………………. 11

Urinary system………………………………………………………. 19

Gynecological cancer……………………………………………… 20

Male reproductive cancer………………………………………. 23

Hematopoietic and lymph node cancer………………….. 25

Thyroid and other endocrine…………………………………. 26

Brain……………………………………………………………………… 26

Connective and soft tissue can- 26

Unknown cancers………………………………………………….. 26

Summary………………………………………………………………………….. 27

Recommendations……………………………………………………………. 27

References……………………………………………………………………….. 28

Appendices

Appendix A: Data sources………………………………………. 34

Appendix B: Cancer site classification: ICD-O-3………. 35

Appendix C: Methodology……………………………………… 36

Cancer in Nunavut: 1999-2011 3

Executive Summary Cancer is the leading cause of mortality in Nunavut and is a significant cause of illness with an average of 59 cases per year from

1999 to 2011.105 Although the 2011 numbers are preliminary, the age-standardized incidence rate (ASIR) of cancer for Nunavut in

2011 was 362.3 per 100,000 as compared to the Canadian rate of 406.0 per 100,000.15 The epidemiology of cancer in Nunavut is

distinct from Canada in leading cancers as well as gender distribution.

Nunavummiut experience higher rates of lung, colorectal, oral and digestive cancers and lower rates of reproductive, hematopoiet-

ic, bladder and thyroid cancers than Canadians. The top 5 cancers affecting Nunavummiut between 1999 and 2011 are: (1) lung, (2)

colorectal, (3) breast, (4) oral and (5) prostate. These cancer groups account for 68% of all cancers. The female Nunavummiut ASIR

exceeds the national rate by 30%, while the male Nunavummiut ASIR is 52% lower than the national rate.15 These differences in

cancer rates may be attributable to variance in demography, heredity, health services, environmental exposures, lifestyles and

illness patterns.

There are multiple programs in place in Nunavut that address cancer risk factors. Amongst them are: Tobacco Reduction Strategy,

Nutrition North and Public Health immunization programs. Further efforts are required to promote healthy lifestyles and environ-

ments as well as to prevent chronic and communicable diseases. Accessible screening programs are also needed in communities to

enable early detection and treatment to improve prognosis.

List of Abbreviations ASIR Age standardized incidence rate

BMI Body mass index

COPD Chronic obstructive pulmonary disease

EBV Epstein-Barr virus

HPV Human papilloma virus

HTLV-1 Human T-cell lymphotropic virus type 1

ICD-10 International Classification of Disease, 10th

revision

ICD-O-3 International Classification of Diseases Oncology,

3rd revision

NWT Northwest Territories

TB Tuberculosis

4

Background: Nunavut cancer risk factors Nunavut is the largest, northern most territory in Canada with an 85% Inuit population. The population of 33,551 people is spread

over 25 fly-in communities covering 2,093,190 km2.

The demographic distribution of Nunavut differs

from Canada, with the majority of the population un-

der 25 years (Figure 1). The life expectancy of Nu-

navummiut at birth is trending up (72.1 years) but is

still 8.5 years lower than Canada (80.6 years).106 The

crude birth rate in Nunavut is 2.3 times the national

average and the total fertility rate is 1.8 times the na-

tional average.104

Healthcare service delivery is different in Nunavut

than the rest of Canada due to its remoteness. Each

community has a health centre with Community Health

Nurses who provide the majority of health services.

The average nurse to population ratio in communities

(excluding Iqaluit) is 1:268. There are 29.5 physician

positions, half of which are staffed by short-term locums, with permanent positions in Iqaluit, Rankin Inlet, Cambridge Bay and

Arviat.

If a patient’s condition exceeds the capacity of the health centre,

they are taken by medevac or scheduled medical travel to a major

health centre (Figure 2). There is generally no specialty diagnostic

equipment (e.g. mammography) or specialists (e.g. oncologists) in

most communities, impacting availability and timeliness of services.

Cancer screening, diagnosis and treatment often require travel, sep-

arating patients from their social networks within communities.

Housing has health impacts influencing communicable disease

transmission and environmental contaminant exposure (e.g. envi-

ronmental tobacco smoke). Nunavut households are more crowded,

having an average of 3.7 people per household compared to 2.5

people in the rest of Canada, potentially affecting cancer risk.65, 103

Contaminant concentrations in the Arctic are affected by global wind and water patterns, bioaccumulating in marine mam-

mals.38 Contaminants found include: (1) polychlorinated biphenyls (PCBs), (2) pesticides, (3) organochlorines and (4) heavy metals

(e.g. mercury).38 Pollutants can affect cancer risk by mimicking hormones and interacting with nutrients and other contaminants.38

Physical activity level has decreased due to a western lifestyle. Canadians were 7% more physically active during leisure-time

than Nunavummiut.109 Males were consistently more physically active in both the Canadian and Nunavut population, with the ex-

ception of non-aboriginal males in Nunavut.109 Inuit in Nunavut were 10% more active than their non-aboriginal Nunavummiut

counterparts.109 Overall, Nunavummiut have significantly lower levels of physical activity than Canadians, potentially contributing

to the higher rate of some cancers.108

Figure 2. Medical travel patterns59

Figure 1. Age-groups as a percentage of total population, Canada and Nunavut, 2011101


Dietary patterns in Nunavut have historically been distinct from Canada; this pattern is currently in flux.39, 96, 110 Traditional

foods are high in nutrients including macronutrients, vitamins, antioxidants and minerals.55, 66, 67 In a western diet, fruits and vege-

tables are an important nutrient source. As refined, store bought foods become a bigger part of diets, there is a loss of the tradi-

tional source of nutrients without replacement with fruits and vegetables.68, 96, 108 Nunavut’s rate of fruit and vegetable consump-

tion is consistently, significantly lower than the national age-standardized rate (ASIR) by an average of 75%.108

Further complicating nutrition in Nunavut is food insecurity, which impacts overall diet quality.58 The ASIR for those living with

moderate or severe food insecurity in Nunavut is 37.8 per 100,000, which is 5 times higher than the national average.109 Diet is an

important protective factor in cancer prevention; poor diet quality and nutrient deficits may contribute to higher cancer rates.

Substance use in Nunavut is distinct from Canada, specifically tobacco and alcohol use. Nunavut exceeds the Canadian ASIR for

current daily or occasional smokers by 3.4 times with 60% of the population smoking. Inuit in Nunavut smoke 1.4 times more than

Inuit in Canada, and non-aboriginals in Nunavut smoke 1.6 times more than Canadians.109 The smoking rate is 14% higher for Nu-

navut females than males, unlike Canada where the male rate exceeds the female rate by 31%. Ninety percent of households in

the Inuit Health Survey had at least one smoker with individuals smoking an average of 10-13 cigarettes per day.39 The higher to-

bacco use in Nunavut is reflected in the higher rate of some cancers.

Alcohol is controlled in Nunavut; some communities prohibit alcohol and others regulate it. The reported Nunavut ASIR for heavy

drinking ( ≥5 drinks per occasion at least monthly in the past year) is 4% lower than Canada for the 10 communities included.109

Males in both national and territorial populations have a higher rate of heavy drinking.109 Within Nunavut, the non-aboriginal pop-

ulation exceeds the Inuit population by 1.4 times for heavy drinking.109 Literature indicates more heavy drinking in aboriginal and

Inuit populations; however, Inuit in Nunavut have a 55% lower rate of heavy drinking than Inuit outside Nunavut.78, 109 Heavy

drinking is only one measure of alcohol use and does not describe binge drinking, moderate use or chronicity of alcohol use.

Infection is an important contributor to the burden of cancer. In 2008, diagnosed cancers attributable to infection was globally

16.1% (7.4% for developed regions and 22.9% for developing regions).36 The primary communicable diseases impacting cancer risk

in Nunavut are: (1) tuberculosis (TB), (2) human papilloma virus (HPV), (3) Epstein-Barr virus (EBV), (4) viral hepatitis, (5)

Helicobacter pylori (H. pylori) and (6) human T-cell lymphotropic virus type 1 (HTLV-1). 39, 80, 82, 90, 99 Nunavut has patterns of com-

municable disease that differ from Canada, potentially contributing to higher rates of some cancers.

Chronic conditions are thought to affect cancer risk through inflammation and impact on the endocrine system.11 Diabetes

incidence in Nunavut has remained relatively stable between 2005 and 2011 and does not significantly differ from the national

rate.108 Overall, in 2011 diabetes had a 3.1% prevalence in Nunavummiut.88 Chronic obstructive pulmonary disease (COPD) has

trended down between 2005 and 2011.88 The 2011 ASIR for Nunavut was 23.7 per 100,000, which is 6.2 times higher than the na-

tional average.108 Overall, in 2011 COPD had a 14.3% prevalence in Nunavummiut.88

Adipose tissue is active endocrine tissue that affects hormone levels. Therefore, excess body fat can impact cancer risk.11 From

2003 to 2012, people who are overweight or obese has steadily trended up in Canada with an average ASIR of 49.6 per 100,000.108

Nunavut sporadically exceeds the Canadian ASIR with a rate fluctuating between 52.7 and 63.7 per 100,000, which is on average

1.2 times higher than the national rate.108 Only Nunavut’s female rate is consistently, significantly higher than the national female

rate.108 The rate of chronic conditions is likely mirrored in the increased rate of some cancers in Nunavut.

6

Cancer overview Approximately 40% of Canadians will develop cancer and it is also the national leading cause of death.16 Nationally, lung, breast,

colorectal and prostate cancers account for 52% of cases and cancer is the fourth most costly disease accounting for $2.6 billion in

direct healthcare costs.16

A total of 773 Nunavummiut (405 female, 368 male) were diagnosed with cancer between 1999 and 2011. For Nunavummiut, can-

cer was the leading cause of death between 2000 and 2009. During this period Nunavut’s age-standardized mortality rate exceeded

the national rate 2.2-fold.105

The cancer pattern among Nunavummiut is different than Canadians (Figure 3). Comparing the Canadian and Nunavut ASIR, lung,

oral and digestive cancers exceed the national rate whereas reproductive and hematopoietic cancers are lower, a finding consistent

with other circumpolar regions.42 In 2011, the all-cancer ASIR was lower for Nunavummiut (362.3 per 100,000) than Canada (406.0

per 100,000).15 The gender-specific ASIR patterns differed with Nunavummiut females exceeding Canadian females by 30% (481.4

versus 369.0 per 100,000) and with Nunavummiut males having a 52% lower rate (239.4 versus 456.0 per 100,000) than Canadian

males.15

Overall, both Nunavut and Canada have lung, colorectal and breast or prostate cancer in the top 5 cancers. The leading 5 sites for

females nationally are: breast, lung, colorectal, body of uterus and thyroid.15 Whereas the leading 5 sites for females in Nunavut

are: lung, colorectal, breast, oral and kidney.

Canadian females appear to be more affect-

ed by reproductive cancers while Nu-

navummiut females appear to be more af-

fected by lung and colorectal cancer.

The leading 5 sites for males nationally are:

prostate, lung, colorectal, bladder and Non-

Hodgkin lymphoma.15 The leading 5 sites for

males in Nunavut are: lung, colorectal, oral,

prostate and kidney. Canadian males appear

to be more affected by reproductive cancers

while Nunavummiut males appear to be

more affected by lung and colorectal can-

cer.

Since cancers have a long latency period,

current cancer trends are reflective of fac-

tors prevalent in the population decades

ago. With changing lifestyles and diet, it is

likely that cancer patterns will change as

Lung Colorectal Oral Esophagus Stomach Kidney Bladder Liver PancreasNon-Hodgkin

LyphomaLeukemia Thyroid Brain Breast Cervix Uterus Testis Prostate

2.93 1.42 2.82 2.94 0.19 1.67 0.26 0.49 2.44 0.30 0.05 0.24 0.61 0.61 0.94 0.13 1.58 0.32

0

1

2

3

4

Ra

tio

Figure 3. Ratio of Nunavut 3 year moving average and Canadian age standardized incidence rate, 2011

Higher Canada Rate

* Unable to calculate rate ratio for: Hodgkin's Lymphoma, Multiple Myloma, Melanoma and Ovary as there were no Nunavut cases.

42%34% 39%

25%

20%

23%

19%

10%

8%

6%

7%8%

4%4%5%

5%2%

5%4%

5%

3%3% 2%

3%3%3%2%

2%2%3%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Female Male Nunavut

Figure 4. Top 10 cancer groups*: Proportion by gender and Nunavut, 1999-2011

Lung Colorectal Breast** Oral Prostate Kidney Stomach Cervix Pancreas Esophagus Brain Leukemia Thyroid

* "Other" and "unknown" categories excluded from calculating top 10 cancer groups

** 1 male breast cancer case excluded from analysis


Lung & Bronchus Cancer

Lung cancer is the leading cancer amongst Nunavummiut with 247 cases (114 female, 133

male) accounting for 32% of reported cancer cases between 1999 and 2011. Other respiratory

tract cancers accounted for an additional 1% of reported cancer cases with 7 cases (3 female, 4

male) between 1999 and 2011.

Nunavut’s lung cancer rate is amongst the highest globally and is 3 times higher than the Cana-

dian rate.27, 107 The top three histologies are: squamous cell carcinoma (SCC), non-small cell

carcinoma, and unspecified small cell carcinoma . The development of lung cancer is complex

with risk factors working both independently and synergistically.

What are the risk factors for lung cancer?

1.

2.

3.

Family history of disease, independent of smoking, increases the chance of developing lung cancer 1.4-fold

[1.2-1.7].73 There are numerous genes and mechanisms implicated in the risk of developing lung cancer.33, 54

For example, the p53 gene mutation occurs in 33% of lung cancers and this percentage increases with tobacco

consumption.33, 54 Another example is genomic polymorphism of the XRCC1 gene, implicated in DNA repair,

which increased lung cancer chances 1.9-fold [1.3-2.9] independent of smoking.47

Gender also influences risk, not only for biological factors like hormones but also for gender-specific roles

that dictated exposure to carcinogens.29, 48 For example, women were more often exposed to environmental

tobacco smoke and men were more often exposed to occupational carcinogens.29

Infection and inflammation are well-established risk factors in cancer development, thus acute and

chronic illness as well as infectious diseases contribute to cancer risk.33

Acute illness in never smokers, like pneumonia history, increases cancer risk 1.4-fold [1.1-1.7]. For those with

chronic illness like COPD, chronic bronchitis or emphysema, the risk increases 1.5-

fold [1.2-1.9].9 In 2011, the Nunavut prevalence for COPD was 14.3%.88

Infectious diseases increase lung cancer risk independent of smoking: TB increases

risk 1.9-fold [1.5-2.5] and HPV increases the risk of SCC 3.5-fold [1.7-7.5].9, 19, 118 In

Nunavut, the average TB rate is 30 times the national rate; at this time the HPV inci-

dence rate is not available.88

In Nunavut, respiratory-related concerns are the primary reason for people access-

ing community health centres.88 The high occurrence of chronic and infectious diseases in Nunavut likely con-

tributes to higher lung cancer rates experienced by Nunavummiut.

Quick facts

Leading cancer site in Nunavut

Average of 19 cases per year

Average age at diagnosis 66 years

62% mortality within one year of diagnosis

8

Environmental Factors

Smoking is the primary etiologic agent implicated in lung cancer, increasing risk 20-fold, and is thought to be responsible

for up to 90% of cases in countries where smoking is common.2 Smoking also works synergistically with infectious diseases

and has been found to increase HPV susceptibility, further increasing lung cancer risk.19

Smoking has been found to alter gene expression and transcription.7 Many genes return

to near normal levels after smoking cessation; however, there are genes that are either

slow to recover or do not normalize even decades after smoking cessation.7 These find-

ings highlight the importance of both never smoking as well as smoking cessation.

Presently, 60% of Nunavummiut 12 years or older report smoking, which is 3 times the

Canadian average. The tobacco use rate in Nunavut is likely a major contributing factor

to the higher lung cancer rate experienced by Nunavummiut.

Carving is an important industry in Nunavut. With the introduction of power tools in

the 1980s, the health impacts have changed.113 Power tool users are exposed to 90 times more dust than non-users.113

This dust, whether it be rock or animal product, has been associated with res-

piratory inflammation.113

In a study of 75 of Nunavut’s carving rock quarries, four were noted to have

asbestos.6 Another study analyzing territorial rock samples found that 19% of

samples had tremolite and 7% of samples had chrysotile, substances that are

part of the asbestos family.113 Asbestos has long been linked to lung cancer

development.

A 2003 study of carvers found that only 58% wore dust masks.113 Of these

individuals, only 28% always wore a mask, 55% mostly to sometimes wore a

mask and 16% did not often wear a mask.113 Thus with technological changes,

rock composition and lack of personal protection, carvers are potentially at

increased risk of lung cancer.

Other environmental risk factors independent of smoking include: environmental tobacco smoke, which increases

risk 1.3-fold [1.2-1.4] and cooking oil fumes (moderate levels of cooking) which increases risk 3-4-fold [1.5-8.9].49, 111, 117

4.


What are lung cancer rates in Nunavut and how do we compare to the rest of Canada?

Are there regional differences in lung cancer rates across Nunavut?

Of all the regions, Baffin had the highest rate (76.3

cases per 100,000) followed by Kivalliq (50.6 cases per

100,000) and then Kitikmeot (44.5 cases per 100,000).

Looking at the number of cases, Baffin had the highest

proportion of cases (65%) followed by Kivalliq (22%)

and then Kitikmeot (13%).

The Nunavut ASIR has generally

trended down over time but still

significantly exceeds national and

NWT rates. In fact, the Nunavut

rate is 3 times higher than the

national rate.

Lung cancer rates are reflective

of smoking patterns, but lag

about 20 years.2 The noted

downward trend is thought to be

associated with historic efforts in

smoking cessation.2

Are there age-related trends in lung cancer incidence in Nunavut?

In Nunavut, the average age at diag-

nosis was 66.2 years (range 36-92

years, standard deviation 9.7 years).

35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 80-84 85+

Incidence Rate 6.98 24.77 20.12 106.31 160.38 580.00 1248.961683.501926.781333.331244.81

0

500

1000

1500

2000

2500

Ra

te p

er

100

,00

0

Figure 7. Lung Cancer Incidence Rate per 100,000 by Age Group, Nunavut, 1999-2011

Nunavut Baffin Kivalliq Kitikmeot

Incidence Rate 63.29 76.34 50.62 44.50

0

10

20

30

40

50

60

70

80

90

Rat

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00,0

00

Figure 6. Lung Cancer Average Incidence Rate per 100,000 by Region, 1999-2011

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut* 258.75 297.06 313.51 284.12 256.68 217.56 220.85 179.09 161.72 164.33 157.49

NWT** 34.00 62.50 62.50 84.80 70.30 70.10 73.30 76.30 56.10

Canada^ 58.70 57.90 57.00 57.40 57.70 56.90 56.00 55.66 55.62 53.71 53.78

0

50

100

150

200

250

300

350

Rat

e p

er 1

00,0

00

Figure 5. Lung Cancer, Age-Standardized Incidence Rate per 100,000 for Canada, Nunavut and Northwest Territories, 2001-2011105

* 3-year moving average.**Data from CANSIM table 103-0553. Blank cells indicate unavailable data.^ Data CANSIM table 103-0553. 2008 data onward are estimates from personal communications with Public Health Agency of Canada.

10

Are there gender-related trends or differences in lung cancer rates in Nunavut?

Nationally, males have a significantly higher rate than females; this difference is consistent over time. In Nunavut, the male rate

slightly exceeds the female rate 2005 to 2010; however, the rate difference by gender does not significantly differ over time.

Compared to Canada, the Nunavut 2011 rate for females was 3.5 times higher and for males was 2.1 times higher; the magni-

tude of this difference by gender is also true for the overall Canadian Inuit population as compared to Canada.20 Within the

circumpolar region, the Canadian lung cancer incidence exceeds Alaska and Greenland by 1.5 times in men and 2-3 times in

women.27

What mortality data are available for lung cancer?

Death clearance data are obtained from Statistics Canada and are available for years 1999-2008. For Nunavummiut diagnosed

with lung cancer, 62% died within one year of diagnosis.

Discussion: What does this information mean for Nunavummiut?

Nunavummiut experience much higher rates of lung cancer as compared to Canada. Higher rates of infectious and chronic dis-

ease as well as tobacco use are likely major contributing factors to Nunavut’s lung cancer rate.

Creating smoke-free environments is important; legislated and home smoking bans effectively reduce nicotine dependence and

promote smoking cessation.4 Smoking bans are also shown to positively affect non-smokers, reducing presentation of inflamma-

tory lung conditions like asthma.4 Continued implementation of the Nunavut Tobacco Reduction Strategy is pivotal to reducing

cancer risk.

Further efforts in infectious and chronic disease prevention, smoking cessation and early detection are pivotal to curtailing lung

cancer rates and improving prognosis. However, impacts may take years to manifest due to a long latency period between risk

factor exposure and lung cancer development.

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut Female* 294.76 338.19 342.28 316.89 249.85 207.03 197.82 171.53 146.64 146.77 175.87

Nunavut Male* 242.10 277.70 309.15 275.42 273.30 222.94 238.88 186.41 180.06 182.88 139.32

Canadian Female** 45.10 45.70 45.60 46.30 47.60 47.90 47.20 51.00 47.00 48.00 51.00

Canadian Male** 77.00 74.50 72.40 72.30 71.10 69.10 67.80 67.00 66.00 66.00 65.00

0

50

100

150

200

250

300

350

400

Rat

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er 1

00,0

00

Figure 8. Lung Cancer, Age-Standardized Incidence Rate per 100,000 for Canada and Nunavut by gender, 2001-201112-15, 105

* 3-year moving average used**Data from CANSIM table 103-0553, with the exception of 2008-2011 data which are estimates obtained from Annual Canadian Cancer Society Reports.


Colorectal cancer is the second leading cancer affecting Nunavummiut, accounting for

19% of cancer cases diagnosed between 1999 and 2011. In the circumpolar region, colo-

rectal cancers account for 15% of Inuit cancer cases; this is expected to trend up with

changing lifestyles.27 Consistent with literature, the predominant histological type of

colorectal cancer in Nunavut is adenocarcinoma (91%).

What are the risk factors for colorectal cancer?

1.

2.

3.

4.

Hereditary factors are thought to contribute 12-13% to risk.34 Examples of known susceptibility genes

include: APC gene which is associated with polyposis, MSH2 and MLH1 genes which are implicated in non-

polyposis colorectal cancer syndrome.5 Family history impacts risk with a greater than 2-fold increase in risk

when at least one first-degree relative is diagnosed.5, 10 The risk of developing colorectal cancer after the age

of 40 years was calculated to be 4.7% [4.0-5.6%] for the general population and 9.6% [6.3-14.2] for those with

a family history of disease.10

Obesity (body mass index (BMI) ≥ 30 kg/m2 ) is consistently associated with higher risk of colorectal cancer

and is found to increase risk 1.2-fold [1.1-1.3].79 The risk is higher in men and is consistently higher in both

genders for developing cancers of the colon than rectum.11 For colorectal cancer, obesity is estimated to con-

tribute 28-35% in men and 14-21% in women for the United States and Europe.11 One analysis found that for

every 2kg/m2 increase in BMI there was an associated 1% increase in colorectal cancer risk.79

Chronic illness like inflammatory bowel disease is thought to increase risk.94 One meta-analysis deter-

mined risk for colorectal cancer increased 2.5-fold [1.3-4.7] with Crohn’s disease, with risk accumulating over

time.18 The results were similar for ulcerative colitis.18 Diabetes is also implicated in colorectal cancer risk; in

one meta-analysis where physical activity and BMI were controlled for, there was a 1.3-fold [1.2-1.5] increase

in risk.70

Lifestyle factors impact colorectal cancer risk. Alcohol has a dose relationship, increasing risk by 5% [1-9%]

for colon and 9% [8-12%] for rectal cancer with 25g/day and

21% [5-39%] for colon and 42% [30-55%] for rectal cancer

with 100g/day.32

Diet is correlated with colorectal cancer risk where fruit, veg-

etable and fish consumption is found to be protective (i.e.

decrease risk) and red meat consumption is found to in-

crease risk.41 Physical activity is also found to be inde-

pendently protective.50

Quick facts

Second leading cancer site in Nunavut




Digestive System:

Colorectal Cancer

12

What are colorectal cancer rates in Nunavut and how do we compare to the rest of Canada?

Are there regional differences in colorectal cancer rates across Nunavut?

Are there age-related trends in colorectal cancer incidence in Nunavut?

In Nunavut, the average age at

time of diagnosis 59.9 years.

However, age ranged between

23-90 years (standard deviation

13.7 years).

Of all the regions, Baffin had the highest rate (41.2 cases per

100,000) followed by Kitikmeot (34.8 cases per 100,000) and

then Kivalliq (30.4 cases per 100,000).

Looking at the number of cases, Baffin had the highest propor-

tion of cases (59%) followed by Kivalliq (24%), then Kitikmeot

(17%).

In Nunavut, there were 146

cases (68 female, 78 male) di-

agnosed between 1999 and

2011.

Overall, the Nunavut ASIR has

trended down over time and as

of 2011 it was 1.4 times higher

than the national rate.

With the exception of 2004,

2010 and 2011, Nunavut signif-

icantly exceeds the national

rate.


Incidence Rate 37.29 41.23 30.37 34.84

0

5

10

15

20

25

30

35

40

45

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Figure 10. Colorectal Cancer Average Incidence Rate per 100,000 by Region, 1999-2011

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut* 147.13 126.55 113.35 75.85 108.61 118.16 143.79 104.77 88.56 61.07 69.89

NWT** 111.40 107.20 106.20 110.40 82.90 99.40

Canada^ 51.70 51.30 49.90 50.70 50.60 49.50 49.70 50.10 49.23 47.82 49.22

0

20

40

60

80

100

120

140

160

Rat

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Figure 9. Colorectal Cancer, Age-Standardized Incidence Rate per 100,000 for Canada, Nunavut, and Northwest Territories, 2001-2011105


20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 80-84 85+

Incidence Rate 2.91 8.91 3.14 17.44 24.77 85.51 112.22 168.40 201.74 395.50 561.17 642.26 1600.00 207.47

0

200

400

600

800

1000

1200

1400

1600

1800

Ra

te p

er

100

,00

0

Figure 11. Colorectal Cancer Incidence Rate per 100,000 by Age Group, Nunavut, 1999-2011


Are there gender-related trends or differences in colorectal cancer rates in Nunavut?

With the exception of 2002, colorectal cancer rates do not significantly differ between men and women. While the female rate

generally exceeds the male rate, this is not always the case. Nationally, the male rate significantly and consistently exceeds the

female rate. According to literature, there is an interaction between gender and BMI with obese men being 30% more likely to

develop colorectal cancer than obese women.11, 79

What mortality data are available for colorectal cancer?


with colorectal cancer, 26% died within one year of diagnosis.


As there are changes in lifestyles and diet as well as a corresponding increase in chronic diseases, it is expected that colorectal

cancer rates will trend up.27 Promotion of healthy lifestyles as well as prevention and control of chronic diseases is paramount to

reducing risk.

Screening provides an opportunity for early case identification and improved prognosis. Targeted screening based on identified risk

factors and population-based screening is an efficient way to make a difference in colorectal cancer prognosis and to potentially

improve survival.

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut Female* 183.68 203.73 167.21 84.70 90.32 92.22 127.51 101.76 97.62 86.49 82.56

Nunavut Male* 120.60 70.90 78.44 72.37 124.71 138.47 156.30 107.51 77.37 36.49 57.28

Canada Female** 42.30 42.10 41.20 41.60 41.50 40.30 40.60 41.00 41.00 41.00 40.00

Canada Male** 63.20 62.60 60.30 61.50 61.40 60.40 60.50 62.00 62.00 62.00 61.00

0

50

100

150

200

250

Rate

per

100

,000

Figure 12. Colorectal Cancer, Age Standardized Incidence Rate per 100,000 for Canada and Nunavut by gender, 2001-201112-15, 105


14

Quick facts

Within top 4 cancers affecting Nunavummiut




Digestive System:

Oral Cancer

Oral cancers are rare in most parts of the world, but common among Inuit as well as popula-

tions in Southern China and North Africa.27 Genetic markers in the Inuit population indicate

Asian heritage, thus oral cancer trends in Southern China are relevant to Nunavut’s popula-

tion.51, 62 In Inuit populations, oral cancer is found to be 25–40 times more frequent than in

non-Inuit populations in the USA, Canada and Denmark.86 This malignancy accounts for 4–7%

of all malignancies in Inuit as opposed to less than 0.1% in non-Inuit populations in USA, Can-

ada and Denmark.86 In Nunavut, oral cancer accounted for 6% of all cancers affecting Nu-

navummiut between 1999 and 2011.

What are the risk factors?

Research suggests that there are overlapping risk factors in oral cancer development: (1) genetics, (2) environment including

toxins like tobacco, alcohol and dietary items and (3) infectious agents like EBV and HPV. These factors can act independently or

synergistically: it was noted that HPV increased risk 2-fold, smoking increased risk 5.8-fold, and HPV plus smoking increased risk

15-fold.95 Differentiated and undifferentiated tumor types are also distinctly influenced by these risk factors.

Oral cancer tumors fall into two major categories: (1) differentiated and (2) undifferentiated. Differentiated tumors are strongly

associated with tobacco use, and risk was found to increase according to duration and frequency of use. Undifferentiated tumors

are strongly associated with viral infection accounting for a 2-4-fold increase in risk.8, 42, 87 In high incidence areas generally undif-

ferentiated nasopharyngeal cancer dominates.8, 42 Further examination is required to determine the dominant tumor grade in

Nunavut.

1. Genetics — Inuit generally retain their risk of oral cancer even after decades of migrating to low prevalence areas,

indicating involvement of genetic factors or early life environmental factors that influence risk.8 Genetic predisposi-

tion is supported by reports of familial clustering with an 8-fold [4.1-14.0] increase in risk experienced by first degree

relatives of Inuit with nasopharyngeal carcinoma.43

Environmental Factors — Presently, 60% of Nunavummiut 12 years or older report

smoking, which is three times higher than the national average.88 In one study, heavy

tobacco and alcohol use accounted for 57% [16–98%] of differentiated tumors.87 It has

also been found that ingesting preserved foods during childhood that contain nitrosa-

mines like Chinese salt-preserved fish, preserved meat and vegetables from North Africa

and traditional Inuit dried fish increases risk of oral cancer later in life.22, 42

Infectious Agents — Worldwide, infection is estimated to contribute 25.6% to oropharyngeal cancer risk and 85.5%

to nasopharyngeal cancer risk.36 Both EBV and HPV have been implicated in oral cancer. EBV is a well-established risk

factor, especially with childhood infection, and evidence is mounting for HPV.8, 42, 45, 87

Inuit children have a distinct pattern of EBV acquisition characterized by early primary infection and high antibody

titres, increasing their risk for oral cancer later in life.82 HPV presence in the oral cavity is associated with a 3.7-fold

[1.5-9.3] increased risk of oral cancer, independent of alcohol and tobacco exposure.99 It is possible that the distinct

pattern of infectious agents in Nunavut contribute to higher oral cancer rates.

2.

3.


What are oral cancer rates in Nunavut and how do we compare to the rest of Canada?

Are there regional differences in oral cancer rates across Nunavut?

Of all the regions, Kitikmeot had the highest rate (12.7 cases

per 100,000) followed by Kivalliq (11.7 cases per 100,000)

and then Baffin (11.3 cases per 100,000).

However, if one looks at the number of cases, Baffin had the

highest proportion of cases (52%) followed by Kivalliq (28%)

then Kitikmeot (20%).

This means that while the rate is highest in the Kitikmeot

region, there is a greater number of people affected by oral

cancer in the Baffin region.

In Nunavut, there were 46

cases (26 female, 20 male)

diagnosed between 1999 and

2011.

Overall, the Nunavut ASIR has

slightly increased over time

and as of 2011 it was three

times higher than the nation-

al rate.

Are there age-related trends in oral cancer incidence in Nunavut?

In Nunavut, the average age at

diagnosis was 52.1 years, alt-

hough age ranged between 12

and 75 years (standard devia-

tion 15.0 years).


Incidence Rate 11.65 11.30 11.65 12.73

0

2

4

6

8

10

12

14

Rat

e pe

r 10

0,00

0

Figure 14. Oral Cancer Average Incidence Rate per 100,000 by Region, 1999-2011

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut* 20.10 20.35 20.13 25.00 18.91 27.62 22.94 22.80 21.65 24.35 24.49

Canada** 9.00 8.80 8.60 8.60 8.80 8.20 9.10 8.65 8.84 8.68 8.69

0

5

10

15

20

25

30

Ra

te p

er

10

0,0

00

Figure 13. Oral Cancer, Age Standardized Incidence Rate per 100,000 for Canada and Nunavut, 2001-2011 105

* 3-year moving average.**Data CANSIM table 103-0553. 2008 data onward are estimates from personal communications with Public Health Agency of Canada.

10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 80-84 85+

Incident Rate 2.32 0.00 0.00 8.91 6.29 10.46 24.77 25.15 35.44 24.06 50.44 145.7 187.0 64.23 0.00 0.00

0

20

40

60

80

100

120

140

160

180

200

Rat

e p

er 1

00,0

00

Figure 15. Oral Cancer Incidence Rate per 100,000 by Age Group, Nunavut, 1999-2011

16

Are there gender-related trends or differences in oral cancer rates in Nunavut?

While Nunavut rates by gender do not significantly differ over time, the female rate generally exceeded the male rate up until

2009. Looking at the national picture, the male rate is consistently higher than the female rate and this difference is significant.

What mortality data are available for oral cancer?


with oral cancer, 9% died within one year of diagnosis.


Overall, oral cancer rates are significantly higher in Nunavut as compared to the national average and are trending up. Factors in-

fluencing this dynamic and potentially affecting cancer risk are diverse and interrelated with genetics, environmental factors and

infectious agents. While it is not possible to change genetic risk, strategic increases in screening targeting individuals who have a

family history of disease can potentially assist with early detection and improve prognosis.

Behaviour modification is also essential to reducing oral cancer rates. Smoking is a major modifiable risk factor; continued efforts

with the Nunavut Tobacco Reduction Strategy are essential to reducing risk. Prevention and control of communicable diseases are

also important in risk reduction (e.g. HPV immunization).

Further work in Nunavut is necessary to determine the tumor grade in order to better tailor risk reduction strategies.

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut Female* 26.23 45.28 41.70 43.73 18.10 28.99 30.65 34.67 21.31 16.47 12.16

Nunavut Male* 14.38 2.89 5.48 12.82 19.52 26.43 16.19 13.51 22.75 32.16 35.00

Canada Female** 5.00 5.40 5.20 5.10 5.20 5.30 5.60 5.00 5.00 5.00 5.00

Canada Male** 12.70 12.50 12.60 12.80 12.60 11.80 13.10 12.00 11.00 11.00 11.00

0

5

10

15

20

25

30

35

40

45

50

Rat

e p

er

10

0,0

00

Figure 16. Oral Cancer, Age-Standardized Incidence Rate per 100,000 for Canada and Nunavut by gender, 2001-201112-15, 105



Esophageal cancer accounted for 1% (10 male) of cancers between 1999 and 2011, averaging 1 case per year with a median

diagnosis age of 70 years (range 42-77, standard deviation 12.47 years). In Nunavut, 70% of the identified cases were adenocarci-

nomas. Nunavut's rate fluctuates but generally exceeds the national rate; in 2011 it was three times higher than the national rate.

For Nunavummiut diagnosed with esophageal

cancer, 33% died within one year of diagnosis.

Incidence and etiology of esophageal cancer

varies by histology.56 The primary determinants

of adenocarcinoma are: (1) gastro-esophageal

reflux disease, (2) high BMI and (3) tobacco use

but it is affected to a lesser degree than squa-

mous-cell carcinoma (SCC).56 SCC is primarily

affected by tobacco and alcohol use; there is

evidence that family history impacts both histo-

logical types.56, 114, 115 There is consistent evi-

dence that diet impacts esophageal cancer risk,

with fruits and vegetables reducing risk.56, 115

Stomach cancer accounted for 3% (8 female, 15 male) of cancers between 1999 and 2011, averaging 2 cases per year with an

average age at diagnosis of 59.9 years (range 30-92, standard deviation 16.7 years). Stomach cancer etiology differs by topogra-

phy.114 Of the 23 cases: 17% were cardia, 39% were non-cardia and 43% were unspecified topography. Nunavut rates increased

between 2001 and 2005 then trend down. For Nunavummiut diagnosed with stomach cancer, 55% died within one year of diagno-

sis.

Statistical modeling suggests the contribution of

risk factors to stomach cancer development is:

28% genes, 10% shared environmental factors

and 62% environmental factors.63

Worldwide, the population attributable fraction

of infectious agents in non-cardia gastric carci-

noma is 74.7% with H. pylori most strongly as-

sociated.36 In Nunavut, 50 to 60% of adults test-

ed positive for H. pylori exposure.39, 80 Over-

crowding, number of siblings and narrow age

gap between siblings independently increase

risk of acquiring H. pylori infection.65

Other factors consistently associated with increased risk of stomach cancer are: (1) peptic ulcers and chronic gastritis, although

both are associated with H. pylori infection, (2) ionizing radiation, (3) pernicious anemia and (4) nitrosamine compounds found in

preserved meats.63 Fruit and vegetable consumption, independent of other dietary factors, reduces stomach cancer risk.63

Digestive System:

Esophagus, Stomach, Liver, Pancreas, Other Gastrointestinal

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut* 15.95 11.41 7.45 8.81 13.37 5.92 4.56 0.00 4.88 7.93 11.78

Canada** 3.6 3.7 3.8 3.7 3.8 3.7 3.8 3.9 4.0 3.9 4.0

0

2

4

6

8

10

12

14

16

18

Rat

e p

er 1

00,0

00

Figure 17. Esophagus Cancer Age-Standardized Incidence Rate per 100,000 for Nunavut and Canada, 2001-2011105


2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut* 13.38 20.99 28.71 32.69 32.96 23.21 28.38 22.04 22.04 5.88 1.29

Canada** 8.2 7.8 7.8 7.9 7.7 7.5 7.3 7.3 7.2 6.8 7.0

0

5

10

15

20

25

30

35

Ra

te p

er

10

0,0

00

Figure 18. Stomach Cancer Age-Standardized Incidence Rate per 100,000 for Nunavut and Canada, 2001-2011105


18

Liver cancer accounted for 1% (2 female, 4 male) of all cancers between 1999 and 2011, averaging 0.5 cases per year. The aver-

age age at diagnosis was 62.2 years (range 49-78, standard deviation 12.2 years). The Nunavut gender ratio is consistent with liter-

ature where the male rate is 2-4 times higher than the female rate.85 There are too few cases to trend; however, this cancer is on

the rise in the Canadian population, an increase attributed to increasing viral hepatitis rates.35, 116

Viral hepatitis plays a major role in the develop-

ment of primary liver cancer, with chronic infec-

tion being associated with 80% of incident cases

globally.94

The percentage of liver cancer cases in devel-

oped countries attributable to Hepatitis B infec-

tion is 23% and for Hepatitis C is 20%.85 In the

Canadian Arctic the prevalence of Hepatitis B is

about 5% and Hepatitis C is between 1-18%.83

Other recognized liver cancer risk factors in-

clude: (1) Afloatoxin, a group of mycotoxins

found in improperly stored foods, (2) alcohol

consumption, with 25 g/day increasing risk 1.2-

fold [1.1-1.3] and with 100g/day further increasing risk to 1.8-fold [1.5-2.2].25, 32 Alcohol works synergistically with cirrhosis and

Hepatitis C to significantly increase risk, (3) tobacco use, which increases risk 1.6-fold [1.3-1.9], (4) obesity (BMI ≥ 30), which in-

creases risk 1.9-fold [1.5-2.4] and (5) diabetes, which is an independent factor.25, 44, 71

Pancreatic cancer accounted for 2% of all cancers (11 female, 7 male) between 1999 and 2011, averaging 1 case per year with a

median age at diagnosis of 65 years (range 6-77, standard deviation 19.8 years). Pancreatic cancer in Nunavut was briefly lower

than the national rate between 2005 and 2008,

but generally exceeds the national rate.

For Nunavummiut diagnosed with pancreatic

cancer, 88% died within one year of diagnosis.

This high mortality rate is consistent with litera-

ture.16, 72

Factors contributing to the development of

pancreatic cancer are not well understood;

however, tobacco use is a well established risk

factor increasing risk 1.7-fold [1.5-1.9].44

Other factors associated with disease risk are:

(1) family history of disease (found in 5-10% of

cases), (2) particular genetic alterations (e.g.

BRCA2), (3) long-standing history of type II diabetes (5-10 years), which increases chances of disease 1.5-fold [1.3-1.8], (4) chronic

pancreatitis and (5) diet.57, 75, 98

Other gastrointestinal cancers accounted for 3% of all cancer cases (12 female, 8 male) between 1999 and 2011, averaging 2

cases per year.

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut* 11.41 11.41 0.00 0.00 0.00 7.31 7.31 7.31 0.00 0.97 2.02

Canada** 3.3 3.3 3.2 3.3 3.6 3.7 3.8 3.8 4.0 3.9 4.1

0

2

4

6

8

10

12

Ra

te p

er

10

0,0

00

Figure 19. Liver Cancer Age-Standardized Incident Rate per 100,000 for Nunavut and Canada, 2001-2011105


2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut* 13.39 21.89 29.34 17.67 8.96 1.51 1.51 0.00 13.84 19.79 23.05

Canada** 9.3 9.1 9.4 9.5 9.6 9 9.4 9.5 9.6 9.0 9.4

0

5

10

15

20

25

30

35

Rat

e p

er 1

00,0

00

Figure 20. Pancreas Cancer Age-Standardized Incidence Rate per 100,000 for Nunavut and Canada, 2001-2011105



Urinary System:

Bladder and Kidney Bladder cancer accounted for 1% of cancers

(2 female, 5 male) between 1999 and 2011,

averaging 0.5 cases per year with a median di-

agnosis age of 44 years (range 2-68, standard

deviation 25.3 years).

Nunavut rates appear to be trending up but still

remain a fraction of the national rate. This is

consistent with findings throughout the circum-

polar region that bladder cancer is rare among

Inuit.8

Risk factors include: (1) smoking (associated

with a 2.8-fold [2.2-3.5] risk increase (including

renal pelvis)), (2) exposure to chemical com-

pounds (e.g. benzidine, beta-naphthylamine, polycyclic aromatic hydrocarbons, diesel exhaust), (3) infectious diseases (e.g. Schis-

tosoma haemarobium, HPV) and (4) hereditary factors, which are thought to contribute 7% to risk.34, 44, 76, 92

Kidney cancer accounted for 4% of all cancer cases (14 female, 15 male) between 1999 and 2011, averaging 2 cases per year

with a median diagnosis age of 62 years (range 1-76, standard deviation 19.3 years). Kidney cancer in Nunavut was briefly lower

than the national rate in 2006 and 2007, but otherwise exceeds the national rate.

Lifestyle factors consistently associated with

risk include smoking and obesity. Smoking is

associated with a 1.5-fold [1.3-1.7] risk in-

crease (excluding renal pelvis).44

Obesity is estimated to account for 31-43% of

renal cancers in the United States and Eu-

rope.11 For overweight or obese individuals, it

is estimated that for every 5kg/m2 weight in-

crease there is a risk increase of 24% for men

and 34% for women.91

Other risk factors include: (1) hypertension, (2)

industrial agents such as trichloroethylene

(used as a metal degreaser and chemical addi-

tive) and (3) hereditary factors, which are thought to contribute 7% to risk; this is further supported by the increased risk seen in

those with first degree relatives diagnosed with kidney cancer.24, 28, 34

There is inconsistent evidence around the risk associated with cadmium, uranium, arsenic, nitrate and radon.24 Protective factors

include diets rich in fruits and vegetables.24

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut* 0.00 0.00 0.00 0.66 2.17 2.17 2.20 1.90 1.90 3.87 4.28

Canada** 16.4 16.5 16.9 16.9 16.5 16.5 16.3 16.4 16.8 16.5 16.3

0

2

4

6

8

10

12

14

16

18

Ra

te p

er

10

0,0

00

Figure 21. Bladder Cancer Age-Standardized Incidence Rate per 100,000 for Nunavut and Canada, 2001-2011105


2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut* 9.58 20.71 29.38 27.84 17.32 8.07 8.07 13.41 21.12 22.35 20.39

Canada** 10.5 10.5 10.4 10.6 10.8 11.2 11.9 11.5 11.6 11.5 12.2

0

5

10

15

20

25

30

35

Ra

te p

er

10

0,0

00

Figure 22. Kidney Cancer Age-Standardized Incidence Rate per 100,000 for Nunavut and Canada, 2001-2011105


20

Gynecological Cancers:

Breast, Cervix, Ovary, Uterus (Body), Other

Quick facts: Cervix

Average of 1 case per year



Quick facts: Breast




Genetics — There are multiple genes implicated in gynecological cancers. For example, the BRCA1 and BRCA2

genes play a role in DNA repair.101 With mutation of these genes, the cumulative risk by age 70 for breast cancer is

55% [50-59%] for BRCA1 and 47% [42-51%] for BRCA2.23 For ovarian cancer, the cumulative risk is 39% [34-45%] for

BRCA1 and 17% [13-21%] for BRCA2.23 Genetic factors are thought to contribute 27% to breast cancer risk and 22%

to cervical cancer risk.34

Hormones — Estrogen levels are increased in ovulating women thus any factor influencing ovulation decreases

breast, ovarian and uterine cancer risk including: (1) pregnancy (high frequency and young age at first birth), (2) later

age of menarche, (3) early onset of menopause and (4) removal of ovaries.3, 60, 84

Oral contraceptives also influence risk of gynecological cancers, providing a strong protective effect for ovarian can-

cer (reducing risk 0.50-fold [0.33-0.75]) and also a protective effect for uterine cancer.3, 60, 84 The affect of contracep-

tives on breast cancer is weak with suggestions that older, high-hormone formulas actually increase risk, a risk which

is mitigated in newer, low-dose formulas.60

Lifestyle — With a trend towards adopting a westernized lifestyle, gynecological cancer risk has been increasing in

circumpolar women due to: (1) decreased birth rate, (2) increased mean maternal age at first birth and (3) pattern of

breast feeding (e.g. decreased duration).42, 74, 84 Alcohol also plays a dose-dependent role, increasing breast cancer

risk 1.3-fold [1.2-1.3] with 25g/day and 2.4-fold [2.1-2.8] with 100g/day.32 Smoking is associated with a 1.8-fold [1.5-

2.2] increase in cervical cancer.44 Uterine cancer risk is associated with: (1) obesity (2-3-fold increase in risk), (2) phys-

ical inactivity and (3) diabetes.3

Infectious Agents — Globally, an estimated 70% of invasive cervical cancer cases were associated with either

HPV16 or 18, with an additional 18% of cases attributable to HPV strains 31, 33, 35, 45, 52 and 58.99 The prevalence

of oncogenic HPV types (16 and 18) in one Nunavut study was 25.8% [23.8-27.9].52

Nunavut offers a publically funded HPV vaccination program to girls in grade 6 (≥ 9 years). Presently, Gardasil is used

which protects against HPV types 6, 11, 16 and 18 and is found to be 99% effective in girls aged 16-26 years with se-

ries completion.89 Presently, territorial HPV coverage rates are not available.

Gynecological cancers account for 10-15% of all cancers globally and in Nunavut, they account

for 12%.1 Traditionally, Inuit experience lower rates of gynecological cancers than their non-Inuit

counterparts, although with changing lifestyles this trend is changing.42

What are the risk factors for gynecological cancers?

Gynecological cancers are differentially affected by risk factors including: genetics, hormones, life-

style and infectious agents. In considering breast cancer risk, it is important to recognize that

breast cancer is not a single disease but a molecularly distinct group of cancers.101 Each group has

a distinct etiology and pathology due to differences in: (1) estrogen-receptor positivity, (2) progesterone-receptor positivity

and (3) HER2 status and as such are differentially affected by risk factors.101

1.

2.

3.

4.


Breast cancer is the leading cancer type

amongst female Nunavummiut and accounts

for 8% (63 cases) of all cancer cases diagnosed

between 1999 and 2011 (excluding 1 male).

The average age at diagnosis is 53.4 years

(range 25-77, standard deviation 11.3 years).

The rate is below the national and Northwest

territories (NWT) rates; this difference is not

significant.

Cervical cancer accounts for 2% (16 cases)

of all cancer cases diagnosed between 1999

and 2011. The average age at diagnosis is 42.8

years (range 26-60, standard deviation 9.2

years). The rate exceeds the Canadian rate, but

not significantly.

Ovarian cancer accounts for 1% (7 cases) of all

cancer cases diagnosed between 1999 and 2011,

averaging 0.5 cases per year. The median age at

diagnosis was 58 years (range 23-72, standard devi-

ation 17.1 years). The ASIR is generally 1.2 times

lower than Canada.

Uterus (Body) cancer accounts for 0.6% (5 cas-

es) of all cases diagnosed between 1999 and 2011.

The median age at diagnosis was 46 years (range 28

-50, standard deviation 9.3 years). There are too

few cases to trend; however, the ASIR is consistent-

ly lower than Canada.

Other gynecological cancers accounted for

1% of all cancers (8 cases) between 1999 and 2011.

What are Nunavut gynecological cancer rates and how do we compare to Canada?

Are there regional differences in female reproductive cancer rates across Nunavut?

Baffin had the highest breast cancer rate (92.2 cases per

100,000) followed by Kitikmeot (44.5 cases per 100,000) and

then Kivalliq (34.0 cases per 100,000). Baffin had the highest

proportion of cases (47%) followed by Kivalliq (28%) and Ki-

tikmeot (25%).

Baffin had the highest cervical cancer rate (21.7 cases per

100,000) followed by the Kitikmeot (8.5 cases per 100,000).

Baffin had the highest proportion of cases (81%) with the rest of

cases in Kitikmeot (19%). Nunavut Baffin Kivalliq Kitikmeot

Breast 33.59 92.16 34.03 44.47

Cervix 8.30 21.67 0.00 8.47

0102030405060708090

100

Rat

e p

er

10

0,0

00

Figure 25. Breast and Cervical Cancer Average Incidence Rate per 100,000 by Region, 1999-2011

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut* 3.70 6.15 8.09 10.65 10.98 8.05 18.17 20.68 20.31 10.15 7.06

NWT** 0.00

Canada^ 8.20 8.00 7.80 7.70 7.30 7.50 7.80 7.37 7.89 7.43 7.47

0

5

10

15

20

25

Ra

te p

er

10

0,0

00

Figure 24. Cervical Cancer, Age-Standardized Incidence Rate per 100,000 for Canada, Nunavut, and Northwest Territories, 2001-2011105


2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut* 55.57 59.10 24.23 32.13 64.51 91.71 96.18 76.91 62.58 64.38 59.92

NWT** 129.70 95.60 206.20 84.80 79.90 85.10 100.00 81.70 109.00

Canada^ 100.40 102.40 96.90 97.20 98.50 98.30 98.30 97.05 99.08 101.07 98.77

0

50

100

150

200

250

Ra

te p

er

10

0,0

00

Figure 23. Breast Cancer in Females, Age-Standardized Incidence Rate per 100,000 for Canada, Nunavut, and Northwest Territories, 2001-2011105


22

Are there age-related trends in female reproductive cancer incidence in Nunavut?

Age-related trends for gynecological cancers in Nunavut cannot be established due to low case counts and sporadic incidence.

For gynecological cancers in Canada, 30% of cases were younger than 50 years and 46% were between 50 and 70 years.1 The ex-

ception to this distribution is cervical cancers where the majority (58%) of cases were under 50 years.1 Given that the majority of

Nunavut’s population is under 50 years, this has implications for both breast and cervical cancer screening.

What mortality data are available for female reproductive cancer? Death clearance data are obtained from Statistics Canada and are available for years 1999-2008. For Nunavummiut diagnosed with:

Breast cancer: 8% died within one year of diagnosis.

Cervical cancer: 8% died within one year of diagnosis.


Nunavut offers a Well-Woman clinic that includes screening for gynecological cancers. The 2011 Nunavut Well-Woman guidelines

recommend cervical screening annually until three normal results are established, then every two to three years for all sexually

active women ending at age 70 if recent tests were normal. The Well-Woman clinics include a clinical breast exam and guidelines

recommend mammography every 1-2 years for low-risk women aged 50 to 69 (for women with a family history, screening should

start 5-years prior to the age of the diagnosed relative). It is ideal that Well-Woman clinics combine reproductive care and cancer

screening as a study in Nunavik found cervical screening to be related to accessing healthcare for reproductive care and family

planning.21

One systematic review found that in a follow-up of invasive cervical cancer cases, 54% [46-66%] of the women had a history of nev-

er being screened or being inadequately screened.102 This quantifies the potential to improve early detection and thus improve the

prognosis for cervical cancer through screening. In Canada (excluding territories, Quebec, Prince Edward Island), when controlled

for hysterectomy, 74% of women age 20 to 69 had been screened at least once between 2006 and 2008.17 Based on these data,

cervical cancer screening can likely be improved in Nunavut and meaningfully impact case detection.

Cervical and breast cancer screening are essential to early detection and improving prognosis. Presently, cervical screening guide-

lines are being revised and mammography guidelines are not followed due to logistical difficulties of screening in remote commu-

nities. HPV vaccination promotion and sexual health messaging are paramount to lowering cervical cancer rates. In addition, fur-

ther investigation into tumor grade for breast cancer in order to identify specific breast cancer groups may provide insight to tailor

prevention and screening programs.101

25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 80-84 85+

Breast 5.94 0.00 10.46 28.90 85.51 41.34 56.13 138.70 41.63 187.06 128.45 0.00 0.00

Cervix 2.97 6.29 10.46 16.52 5.03 17.72 8.02 12.61 0.00 0.00 0.00 0.00 0.00

0

20

40

60

80

100

120

140

160

180

200

Rate

per

100,0

00

Figure 26. Breast and Cervical Cancer Incidence Rate per 100,000 by Age Group, Nunavut, 1999-2011


Prostate cancer is the third leading cancer site amongst male Nunavummiut and accounts for 3% of all cancer cases (24 cases)

diagnosed between 1999 and 2011. The Nunavut rate is significantly below the national average with the exception of 2003 and

2004. This finding is consistent with other circumpolar regions.8, 37, 42

There are likely both genetic and

lifestyle factors that impact pros-

tate cancer risk. This assertion is

supported by the finding that Inuit

who emigrate are at increased risk

for prostate cancer but their risk

remains 70% lower than the desti-

nation country.8

Non-modifiable factors thought to

be related to risk are: (1) genetics

(e.g. lower androgen receptor ac-

tivity, which is protective) and (2)

increasing age, which increases

risk.46, 93

Modifiable factors thought to be

related to risk are: (1) diet (traditional diets high in omega-3 fatty acids are protective and high-calorie diets increase risk), (2) obe-

sity, which increases risk and (3) physical activity, which is protective.42, 112

Testicular cancer accounts for 0.7% of all cancers (5 cases) diagnosed between 1999 and 2011. There are too few cases to

trend; however, the rate is generally 2 to 5 times lower than the national rate. In recent years, this trend seems to be changing

with the 2010 rate being almost equal to the national rate and the 2011 rate being 1.6 times higher than the national rate.

Testicular cancer risk factors are not well understood but it has been noted to predominantly occur in those of European ancestry

and is most consistently associated with failure of the testicles to descend (4.3-fold [3.6-5.1]), prior testicular cancer history and

family history of disease.26, 31

Other male cancer accounted for 0.4% of all cancers (3 cases) diagnosed between 1999 and 2011.

Male Reproductive Cancers:

Prostate, Testis, Other

What are male reproductive cancer rates in Nunavut and how do we compare to the rest of Canada?

Quick facts: Prostate

3rd leading cancer site in men




Nunavut male reproductive cancer rates have historically been lower than the national average, but with changing lifestyles this

trend is changing.20, 42

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut* 0.00 27.67 63.16 65.77 38.10 18.39 18.41 34.37 29.58 40.73 34.06

NWT** 86.50 154.20 102.80

Canada^ 133.20 123.80 120.40 122.60 121.90 126.10 125.00 113.77 111.21 107.62 107.35

0

20

40

60

80

100

120

140

160

180

Rat

e p

er

10

0,0

00

Figure 27. Prostate Cancer, Age-Standardized Incidence Rate per 100,000 for Canada, Nunavut, and Northwest Territories, 2001-2011105


24

Are there regional differences in male reproductive cancer rates across Nunavut?

Are there age-related trends in male reproductive cancer incidence in Nunavut?

Baffin had the highest prostate cancer rate (14.1 cases per

100,000) followed by Kivalliq (8.9 cases per 100,000) and then

Kitikmeot (8.3 per 100,000). Baffin had the highest proportion of

cases (67%) followed by Kivalliq (21%) and Kitikmeot (12%).

There are too few testicular cancer cases to regionally trend.

Prostate cancer incidence gener-

ally trends up by age group,

sharply declining after 80-84

years.

Testicular cancer cases are clus-

tered between 28 and 34 years.

What mortality data are available for prostate cancer?


with prostate cancer, 0% died within one year of diagnosis.


A reversal of the trend of lower prostate cancer incidence has been noted in Alaskan Inuit and is thought to be attributable to the

adoption of a western lifestyle.69, 100 As high-calorie diets, obesity, and low physical activity become more common and there is an

increase in life expectancy, it is anticipated that there may be a corresponding increase in prostate cancer incidence in the coming

decades.20, 42, 93 Healthy lifestyles and screening are essential to reducing male reproductive cancer risk and improving prognosis.


Incidence Rate 11.57 14.10 8.86 8.25

0

2

4

6

8

10

12

14

16

Rat

e p

er 1

00,0

00

Figure 28. Prostate Cancer Average Incidence Rate per 100,000 by Region, 1999-2011

45-49 50-54 55-59 60-64 65-69 70-74 75-79 80-84 85+

Incidence Rate 5.03 0.00 64.15 75.65 41.63 112.23 128.45 266.67 0.00

0

50

100

150

200

250

300

Ra

te p

er

100

,00

0

Figure 29. Prostate Cancer Incidence Rate per 100,000 by Age Group, Nunavut, 1999-2011


Hematopoietic & Lymph node Cancers:

Hodgkin Lymphoma, Leukemia, Multiple Myeloma, Non-Hodgkin Lymphoma, Other Lymph

Hematopoietic cancers remain lower in Nunavut than nationally. Risk factors differ by cancer type and subgroupings within

each type.

There are no clear, overarching lifestyle or dietary risk factors for leukemia and lymphoma; risk differs by subgroupings. Smoking

has been consistently associated with Hodgkin lymphoma; its effects on other lymphomas is unclear.61 Chemical exposure and radi-

ation exposure in childhood are associated with leukemia.64, 119

Infectious diseases are also associated: (1) EBV is implicated in Hodgkin and non-Hodgkin lymphoma, (2) H. pylori is implicated in B-

cell lymphomas in mucosa-associated lymph tissue, increasing risk 7.2-fold (3) Chlamydia psittaci in eye tissues are linked to B-cell

lymphomas in this area, (4) Campylobacter jejuni is linked with B-cell lymphomas in the small intestine, (5) HTLV-1 is implicated in

Adult T-cell leukemia and lymphoma, and (6) Hepatitis C is associated with non-Hodgkin lymphoma.30, 36, 77, 94

Hodgkin Lymphoma accounted for 2 cases (2 male) between 1999 and 2011 which was 0.3% of all cancer cases and averages

0.2 cases per year. This sample size is too small to provide a meaningful epidemiologic description.

Leukemia accounted for 12 cases (6 female,

6 male) between 1999 and 2011 which was 2%

of all cancer cases and averages one case per

year. The median age at diagnosis was 31.5

years (range 1-67, standard deviation 25.9

years).

Multiple Myeloma has accounted for a

single case between 1999 and 2011 which was

0.1% of all cancer cases and averages 0.1 cases

per year. This sample size is too small to pro-

vide a meaningful epidemiologic description.

Non-Hodgkin Lymphoma accounted for 7

cases (3 female, 4 male) between 1999 and

2011 which was 1% of all cancer cases and aver-

ages 0.5 cases per year. The average age at diag-

nosis was 60.7 years (range 50 -72, standard

deviation 8.8).

Other lymph cancers accounted for 1 case

between 1999 and 2011.

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut* 1.46 1.46 3.97 3.97 8.52 7.20 7.20 2.65 3.85 3.85 5.00

Canada** 15.9 16 16.1 16.8 16.7 16.8 16.9 16.6 16.5 16.6 16.8

0

2

4

6

8

10

12

14

16

18

Rat

e p

er

10

0,0

00

Figure 31. Non-Hodgkin Lymphoma Cancer, Age Standardized Incidence Rate per 100,000 for Canada and Nunavut, 2001-2011105


2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut* 0.93 0.00 0.66 2.24 5.49 6.79 8.57 9.44 8.12 4.75 0.64

Canada** 11.1 11.6 11.9 11.7 11.8 11.9 12.2 12.1 12.1 12.2 12.5

0

2

4

6

8

10

12

14

Rat

e p

er 1

00,0

00

Figure 30. Leukemia Cancer, Age Standardized Incidence Rate per 100,000 for Canada and Nunavut, 2001-2011105


26

Thyroid and Other Endocrine

Thyroid cancer accounted for 1% of all cases (9 female,

2 male) between 1999 and 2011, averaging one case per

year. The average age at diagnosis was 42.3 years (range 22

-66, standard deviation 14.8 years). The Canadian thyroid

cancer rate is trending up especially in women. This is re-

flected globally and is not entirely explained by a change in

diagnostic techniques.40 Since 2003, the Nunavut rate has

been 4-12 times below the national rate.

Histology and grade are both important considerations for

risk factors. Follicular tumors are more common than papil-

lary tumors in regions of iodine insufficiency and differenti-

ated carcinoma are most frequently diagnosed in women.97 In Nunavut, all cases were papillary tumors and grade was unavailable.

Exposure to ionizing radiation in childhood and a history of thyroid abnormalities are the only widely-recognized risk factors for

thyroid cancer.53, 64, 81, 97

Other endocrine cancers accounted for 2 cases (2 female) between 1999 and 2011.

Brain

Brain cancer accounted for 2% of all cancer cases (10 fe-

male, 5 male) between 1999 and 2011. On average brain

cancer accounts for 1 case per year with a median diagnosis

age of 29 years (range 1-81 years, standard deviation 23.6

years).

Because of the small annual case counts, the Nunavut rate is

highly unstable. When the Nunavut brain cancer rate is av-

eraged over the 11-year period under study it does not differ

significantly from the national rate.

Connective & Soft Tissue Cancers:

Bone, Joint, Soft Tissue, Melanoma, Other Skin Bone and joint cancers accounted for 2 cases (1 female, 1 male) between 1999 and 2011. Soft tissue cancers accounted

for 2 cases (2 female) between 1999 and 2011. Melanoma accounted for 4 cases (1 female, 3 male) between 1999 and 2011.

Other skin cancers accounted for 6 cases (4 female, 2 male) between 1999 and 2011.

Unknown Unknown cancers accounted for 2% of all cancer cases (8 female, 9 male) diagnosed between 1999 and 2011.

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut* 11.89 11.89 4.07 1.37 1.37 2.30 2.16 2.16 1.23 1.10 3.20

Canada** 7.4 8.6 8.7 9.5 10.7 10.9 11.6 12.2 12.6 13.0 13.3

0

2

4

6

8

10

12

14

Rat

e p

er

10

0,0

00

Figure 32. Thyroid Cancer, Age Standardized Incidence Rate per 100,000 for Canada and Nunavut, 2001-2011105


2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Nunavut* 7.94 6.23 3.75 10.36 12.68 12.68 3.54 0.00 0.00 1.29 4.16

Canada** 6.4 6.2 6.4 6 6.4 6.3 6.4 6.9 6.9 6.7 6.9

0

2

4

6

8

10

12

14

Rat

e p

er

10

0,0

00

Figure 33. Brain Cancer, Age Standardized Incidence Rate per 100,000 for Canada and Nunavut, 2001-2011105



Summary Cancer is the leading cause of mortality and significantly contributes to illness in Nunavut. Nunavut’s pattern of cancer is distinct

from the rest of Canada with a higher rate of lung, colorectal and oral cancers and lower rates of reproductive cancers. When look-

ing at all cancers combined, the overall cancer rate is higher among Nunavut women when compared to the national rate while

the rate in Nunavut men is a fraction of the national rate.

Nunavummiut have a different risk factor profile than Canada. Factors increasing cancer risk include: higher tobacco use rates,

lower physical activity, dietary patterns, crowded housing conditions, different patterns of infectious diseases and increasing

chronic disease rates. However, the Tobacco Reduction Strategy, federal and territorial nutrition programs, alcohol restriction and

public health immunization programs have likely reduced the risk of some cancers.

Further work is required to lower cancer rates and cancer mortality in Nunavut. Particular focus on prevention and early detection

is required for the top cancers affecting Nunavummiut. Programs already in place regarding tobacco reduction, nutrition and im-

munization are essential to reducing the cancer rate in Nunavummiut. Further programs for screening and healthcare accessibility

are required to enable early detection, thereby improving prognosis and enabling Nunavummiut to remain as close as possible to

their communities for screening and treatment.

Recommendations Timely, complete cancer surveillance data to guide policy:

Regular auditing of the Nunavut cancer registry

Regular reporting schedule

Timely risk factor surveillance data:

Implement surveillance program to collect data on risk factors identified in this report

Advocate for improved representativeness on Canadian Community Health Survey

Cancer prevention strategies:

Continue Tobacco Reduction Strategy

Continue alcohol regulation strategy

Continue Food Security Strategy

Reduce communicable disease transmission (including but not limited to: EBV, HPV, TB, H. pylori)

Targeted early detection strategies:

Continue to improve the quality of the cervical cancer screening program

Review the breast cancer screening program

Colorectal screening program

Obtain further histological grading and molecular information on select cancers to tailor prevention strategies.

28

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34

The Canadian Cancer Registry (CCR): Incident Data

Population Health Information in collaboration with Cancer

Care Ontario identifies incident cancer cases; this data is then

provided to the Health Statistics Division at Statistics Canada.

Nunavut data is available for 1999-2011, with 2011 cases being

provisional. National data is available from 1984 to 2007, with

data from 2008 and onwards being projections done by the

Public Health Agency of Canada.

The CCR provides data on demographic and clinical factors.

Patients are registered according to jurisdiction of residence at

the time of diagnosis. The database is structured to prevent

duplicate person or tumor entry. This information is also linked

with mortality data to ensure database completeness. Cancer

is classified using the International Classification of Diseases for

Oncology, 3rd revision (ICD-O-3).

Limitations: (1) missing data due to out of territory diagnosis

and difficulty in case finding, and (2) timeliness of data, there is

an 18-month delay on data release.

The Canadian Vital Statistics death database

(CVS:D): Mortality Data

The Nunavut Vital Statistics office registers territorial deaths;

this data is provided to the Health Statistics Division at Statis-

tics Canada for inclusion in the CVS:D.

The CVS:D provides data on demographics and cause of death

for residents who died between 1950-2009; cancer mortality

data is available for the period of 1984 to 2009. Nunavut death

clearance data is available from 1999 to 2008.

Cause of death is classified using the International Statistical

Classification of Diseases and Related Health Problems, 10th

revision (ICD-10). To be classified as a cancer death it needs to

be certified by a physician.

Limitations: (1) missing data due to out of territory deaths sec-

ondary to lack of territorial tertiary facilities, (2) timeliness of

data due to out of territory deaths and completing autopsy

reports, and (3) misclassification of cause of death during certi-

fication process resulting in the possible underreporting of

deaths attributable to cancer.

Population Data: Nunavut and Canada

Population projections based on the 5-year national census

data obtained from the Nunavut Bureau of Statistics was used

for the Nunavut population. Population projections based on

the 5-year national census data from Statistics Canada was

used for the Canadian population.

Limitations: Assumptions of growth for projection calculations.

The Canadian Community Health Survey (CCHS):

Risk Factor Data

CCHS is a national, cross-sectional, self-report survey targeting

Canadians 12 years and older. From 2000 to 2005 it was con-

ducted every two years; from 2007 onward it has been done

annually. In Nunavut, 350 individuals from 10 communities

(Iqaluit, Rankin Inlet, Cambridge Bay, Kugluktuk, Cape Dorset,

Igloolik, Pond Inlet, Baker Lake and Arviat) are surveyed each

year providing a 71% coverage rate.

Limitations: (1) non-representative sample and biased infor-

mation due to non-random community selection, (2) self-

report bias, and (3) small sample size.

Inuit Health Survey (IHS): Risk Factor Data

IHS is a cross-sectional, health status survey conducted in Inuit-

inhabited areas of Canada excluding Quebec in 2007 and 2008.

There were 33 coastal and three inland communities targeted.

In Nunavut, 1,923 residents 18 years and older and self-

identified as Inuit were surveyed in 25 communities. An aver-

age of 1.4 people per household participated.

Limitations: (1) Cross-sectional design, (2) self-report bias, and

(3) exclusion of homeless population.

Community Health Service Records (CHSR): Com-

munity Health Centre Visits

The CHSR is an administrative database. When an individual

accesses a health centre, the practitioner completes a CHSR

form listing the reason for accessing services and the ICD-10

code. These forms are then mailed to Iqaluit for entry into the

database.

Limitations: (1) Incorrect codes, (2) incomplete forms, (3)

missing information, and (4) data entry error.

Appendix A: Data sources and Limitations


Appendix B: Cancer site classification: ICD-O-3

Cancer ICD-O-3 Code Oral C00-11

Other buccal cavity & pharynx C09, C12-14

Esophagus C15

Stomach C16

Colorectal C18-20, C26.0

Liver C22.0

Pancreas C25

Other digestive system including small intestine and anal

C17, C21, C22.1, C24, C26.8-26.9, C48.0-48.8

Larynx C32

Lung C34

Other respiratory system C30.0-30.1, C31, C33.9, C38.1-38.8, C39

Melanoma C44 (Type 8720-8790)

Other Skin C44

Breast C50

Cervix C53

Body of uterus C54-55

Ovary C56.9

Other female genital C51, C52.9, C57-58

Prostate C61.9

Testis C62

Other male genital C63

Bladder (including in situ) C67

Kidney C64.9, C65.9

Other urinary system C66.9, C68

Brain C70-72

Thyroid C73.9

Other endocrine C37.9, C74, C75

Hodgkin Lymphoma Type 9650–9667

Non-Hodgkin Lymphoma Type 9590–9597, 9670–9719, 9724–9729, 9735, 9737, 9738, 9811–9818, 9823, 9827, 9837 all sites except C42.0,.1,.4

Other lymph C77

Multiple Myeloma Type 9731, 9732, 9734

Leukemia Type 9733, 9742, 9800–9801, 9805–9809, 9820, 9826, 9831–9836, 9840, 9860–9861, 9863, 9865–9867, 9869–9876, 9891, 9895–9898, 9910, 9911, 9920, 9930–9931, 9940, 9945–9946, 9948, 9963–9964, Type 9811–9818, 9823, 9827, 9837 sites C42.0,.1,.4

Bones and joints C40-41

Soft tissue C38.0, C47, C49

Unknown C42.0-42.4, M-8000 to M-9049, M-9056 to M-9139, M-9141 to M-9589; C76.0-76.8, M-8000 to M-9049, M-9056 to M-9139, M-9141 to M-9589; C77.0-77.9, M-8000 to M-9049, M-9056 to M-9139, M-9141 to M-9589; C80.9, M-8000 to M-9049, M-9056 to M-9139, M-9141 to M-9589; M-9740, M-9741, M-9750 to M-9758, M-9760 to M-9769, M-9950 to M-9962, M-9970 to M-9989

36

Appendix C: Methodology

Age Statistics

For age, the mean is provided as a summary measure for esti-

mates that have a normal distribution. In cases where the

data is skewed the median is provided.

Confidence intervals and statistical significance

Confidence intervals are a measure of variability; when avail-

able the 95% confidence interval is provided in square brack-

ets next to the estimate.

The confidence interval overlap method was used to deter-

mine statistical significance in rate comparisons. The confi-

dence intervals for rate comparisons were calculated using

the Fleiss method.

Three-year moving average

A three-year, simple moving average for Nunavut ASIR data

was used to smooth trends and facilitate interpretation.

Incidence rates: Nunavut & Canada

Nunavut incident rates were calculated from the territorial

cancer registry which is collaboratively maintained with Can-

cer Care Ontario. The 2011 data is considered provisional.

Canadian incident rates were calculated from the CCR.

The cancer registry is a dynamic database, thus incidence

rates may change as more data becomes available.

Age-standardized incident rate (ASIR)

Incident data was standardized to the 1991 Canadian popula-

tion using the direct method. The direct method involves

weighting the ASIRs for each 5-year age group according to

the age distribution of the 1991 Canadian population.

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