Cancer Incidence and Survival Among Métis Adults in Canada: Results from the Canadian Census Follow-Up Cohort (1992–2009)

RESEARCH VULNERABLE POPULATIONS

Cancer incidence and survival among Métis adults in Canada: results from the Canadian census follow-up cohort (1992–2009)

Maegan V. Mazereeuw MPH, Diana R. Withrow PhD, E. Diane Nishri MHSc, Michael Tjepkema MPH, Eduardo Vides MD MPH, Loraine D. Marrett PhD

n Cite as: CMAJ 2018 March 19;190:E320-6. doi: 10.1503/cmaj.170272

ABSTRACT

BACKGROUND: Métis people are 1 of 3 risk (RR) of cancer among Métis and non- CI 1.03–2.48), gallbladder (RR 2.35, 95% Aboriginal groups recognized by the Aboriginal adults using Poisson regres CI 1.12–4.96) and cervix (RR 1.84, 95% Canadian constitution. We estimated sion, and estimated excess mortality CI 1.23–2.76). Métis people had poorer site-specific incidence rates and survival rate ratios using ethnicity-specific life survival for prostate cancer (excess mor for the most common cancers among tables. tality rate ratio 2.60, 95% CI 1.52–4.46). Métis adults in Canada and compared these with rates among non-Aboriginal RESULTS: For all cancers and both sexes INTERPRETATION: We found higher inci adults in Canada. combined, cancer incidence was similar dence for several cancers and poorer sur for Métis and non-Aboriginal adults. vival after prostate cancer among Métis METHODS: We examined responses to the However, incidence was significantly adults. Several of these disparities may 1991 long-form census, including self- higher among Métis adults than among be related to lifestyle factors (including reported Métis ancestry linked to national non-Aboriginal adults for the following tobacco use, obesity and lack of cancer mortality and cancer databases for follow- cancers: female breast (RR 1.18, 95% screening), providing evidence to sup up from 1992 to 2009. We estimated age- confidence interval [CI] 1.02–1.37), lung port development of public health policy standardized incidence rates and 5-year (RR 1.34, 95% CI 1.18–1.52), liver (RR 2.09, and health care to address cancer bur relative survival. We determined relative 95% CI 1.30–3.38), larynx (RR 1.60, 95% den in the Métis people of Canada.

étis people are 1 of the 3 distinct groups named in the led to the genesis of a new Aboriginal people — the Métis people — Constitution Act of 1982 as the “aboriginal peoples of with their own unique culture, traditions, language (Michif), way of Canada,” explicitly defined as “Indian [now referred to life, collective consciousness and nationhood (the Métis Nation).7 Mas ‘First Nations’], Inuit, and Métis peoples of Canada.”1 Aborig Métis constitute 1.4% of the Canadian population, numbering over inal peoples in Canada experience greater poverty and unem 450 000 individuals who are dispersed across the country, with ployment, lower levels of education and higher prevalence of particular concentrations in Ontario and the Prairie provinces.8 several known risk factors for chronic disease (tobacco smoking, The paucity of formal national registration systems for Métis, cou obesity and unhealthy diet) relative to non-Aboriginal Canad pled with the fact that Métis people tend not to cluster in specific ians.2,3 These diverse influences and disadvantages have ulti geographic areas (unlike many Inuit and First Nation communi mately resulted in poorer health outcomes, such as lower life ties), has contributed to underrepresentation of Métis in the health expectancy4,5 and higher prevalences of chronic conditions.3 The literature relative to their share of the population.9 Furthermore, lack of racial or ethnic identifiers in Canadian health databases, no single definition of Métis exists, which often makes compari including cancer registries, has limited our ability to accurately sons between studies and generalization of results challenging. determine and effectively address priorities for chronic disease National data about cancer incidence among Métis are lacking, prevention in these populations.6 and Métis-specific cancer survival has never been estimated. Three The Métis people of Canada are descendants of the offspring of provincial-level studies of cancer incidence among Métis in Can early unions between First Nations women and European fur trad ada had too few cases to produce precise estimates of differences ers. Subsequent intermarriage of these mixed-ancestry individuals between Métis people and the general population.10–12

E320 CMAJ | MARCH 19, 2018 | VOLUME 190 | ISSUE 11 © 2018 Joule Inc. or its licensors RESEARCH E321 Region Region 22 Rurality was a dichoto 21 ISSUE 11 ISSUE | We performed a subgroup analysis to evaluate pat 23 lation living in towns and municipalities outside the com We estimated relative risk (RR) comparing the rate of cancer -Aboriginal ances Respondents were considered to be of non level variable defined by Statistics Canada as the as the mous area-level variable defined by Statistics Canada popu muting zone of larger urban centres (i.e., the non–census metro population). agglomeration area/non–census politan terns of site-specific cancer incidence by region of residence. in Métis and non-Aboriginal adults using 2 Poisson models, the Statistical analysis Incidence of cancer Person-time was accumulated from Jan. 1, 1992. For all cancers combined, follow-up ended at the earliest of date of death or Dec. 31, 2009. For site-specific cancer incidence, follow-up was censored at the date of diagnosis of that cancer if a cancer was diagnosed. Incidence rates were age-standardized using the World Standard Population. was determined according to the province or territory of resi dence on census day. for stability in the estimates, we performed the survival analy survival the we performed estimates, in the stability for cancer types. the 4 most common sis only for Date of death derived vari of death using a each person’s date We ascertained the Canadian as reported in on date or dates of death able based summary files and the Canadian Cancer Mortality Database, tax Registry. Aboriginal ancestry as Métis or non-Aboriginal on the basis We classified respondents the pertaining to Aboriginal ancestry in of answers to questions were asked to select the 1991 long-form census. Respondents to which their ancestors belonged, with cultural group or groups We of ancestries that could be reported. no limit on the number Métis if they reported 2 or fewer ancestries, classified a person as We excluded from the Métis category one of which was Métis. the Indian Act or individuals who reported registration under (or both), given the membership in an Indian Band or First Nation identifier standard gold No people. Métis of nationhood distinct asked about both exists. In later censuses, questions have was chose we definition The ancestry. and identity Aboriginal to the identity and informed by comparisons between responses most of the individ ancestry concepts in later censuses, whereby uals meeting the above-described definition of Métis based pri marily on ancestry also reported Métis identity. ancestry Indian American (North Nations First not were they if try or membership in an only, registration under the Indian Act, Inuit or previously) defined (as Métis Nation), First or Band Indian (Inuit ancestry only). Income, rurality and region quin adequacy income area-level constructed Canada Statistics combined sources all from income total of ratio the using tiles unit to low-income across all members of an economic family cut-offs from the 1991 Census Dictionary. VOLUME 190 VOLUME | 15 We grouped We grouped 19 MARCH 19, 2018 The component The component | 16 Surveil the of -3) -O we excluded Quebec we excluded Quebec CMAJ 17,18

The final cohort for this study was The final cohort for this study was 13 For the incidence analysis, we included included we analysis, incidence the For Briefly, to form the cohort, respondents to cohort, respondents to Briefly, to form the 20 13,14 The Canadian Cancer Registry, an amalgamation of the 13 of the 13 The Canadian Cancer Registry, an amalgamation specific cancer incidence and and incidence cancer site-specific of patterns We examined The Canadian Mortality Database is an administrative data The Canadian Mortality Database is an administrative registries differ somewhat in their methods. In particular, the In particular, the registries differ somewhat in their methods. relied almost exclu Quebec Tumour Registry has historically a different definition of sively on hospital data, which results in which gen date of diagnosis from those in other jurisdictions, Because this definition erally have access to pathology reports. espe death, and diagnosis between time estimated the affects cially for cancers with poor survival, residents from the survival analysis. provincial and territorial cancer registries, includes all cancers includes all cancers provincial and territorial cancer registries, diagnosed in Canadian residents since 1992. survival among Métis people in Canada from 1992 to 2009 and to 2009 and Canada from 1992 Métis people in survival among population. non-Aboriginal their risk relative to the evaluated

individuals aged 25 to 99 years at diagnosis, and excluded individuals aged 25 to 99 years at diagnosis, and excluded those with a death date preceding the diagnosis date. We Métis the in more or 5 of counts case with cancers all included population. For the survival analysis, we included individuals aged 45 to 90 years at diagnosis (as described in the “Statis tical analysis” section, below), and excluded cases registered solely on the basis of the death certificate or autopsy and (which date diagnosis preceding date death with those together accounted for less than 3% of Métis and of non- Aboriginal cancer cases). To ensure a large enough sample size Definitions Diagnosis of cancer We counted multiple invasive cancers in the same individual according to the rules for multiple primary cancers of the International Agency for Research on Cancer. Health and Environment Cohort (pre The 1991 Canadian Census is the largest Cohort) Mortality known as the 1991 Census viously and has been described in population-based cohort in Canada detail elsewhere. Methods data sources Study cohort and form census aged 25 years or older on June 4, 1991 on June 4, or older aged 25 years long-form census the 1991 tax linked to nonfinancial (census day), were probabilistically 1990 and 1991 tax years to add personal summary files for the tax with the census. Those found to have a identifiers not stored years were subsequently matched to the record in one of these (1992–2009) and the Canadian Can Canadian Mortality Database cer Registry (1992–2009). lance, Epidemiology, and End Results Program (US National lance, Epidemiology, and End Results Program (US National Institute). Cancer cancers according to the site recode for the International Clas (ICD Oncology for Diseases of sification composed of 2.7 million individuals who represented a 15% sam composed of 2.7 million individuals who represented older on census day. ple of the Canadian population aged 25 or and containing demo base maintained by Statistics Canada deaths all for information of death) (cause medical and graphic registries. from all provincial and territorial vital statistics RESEARCH E322 with thatamong non-Aboriginaladults wasnumericallylowerfor adults intheOntario/Quebecregion (Figure1). with thegreatestdisparitybetween Métisandnon-Aboriginal cancer sitefor which some variation was observed byregion, tistically significant.Inthesubgroup analysis,lungwastheonly among non-Aboriginaladults,butthesedifferenceswerenotsta stomach and ovary werenumerically higher amongMétisthan both sexes combined. The incidence of cancers of the kidney, colorectal cancersinwomenandformelanomaleukemia in Aboriginal peers,whereastheriskwassignificantlylower for ynx and gallbladder (both sexes combined), relative to their non- (men andwomen),femalebreastcervix,aswellliver,lar adults hadsignificantlyhigherincidenceofcancersthelung Métis womenrelativetotheirnon-Aboriginalcounterparts. incidence wassimilarforMétismenandsignificantlyhigher for was similar for Métis and non-Aboriginal adults Table ( 2). Cancer levels ofincomeandeducation(Table1). inces (Alberta,SaskatchewanandManitoba)tohavelower younger, morelikelytoresideinruralareasandthePrairieprov Relative to non-Aboriginal adults, Métis adults were significantly 1090 cancerswerediagnosedoverabout185 000person-years. Among the11 050adultsaged25to99yearswithMétisancestry, Results University ofToronto(protocol29323). The studywasapprovedbytheresearchethicsboardof Ethics approval We estimated relative survival using ethnicity Survival formed usingSASversion9.4. trolling forincomeandrurality.Allincidenceanalyseswereper first controlling for age andsex,thesecond additionally con cantly overtime,survivalgenerallyimprovedtime. although excessmortalityrateratiostendednottochangesignifi vival ratiostocasesdiagnosedfrom20012009because Survival Standards. tive survivalratioswereage-standardizedtoInternationalCancer additionally controllingforincomeandrurality.The5-yearrela decade ofdiagnosis(1992–2000v.2001–2009),andthesecond parametric survivalmodels,thefirstcontrollingforage,sexand for ethnicity,age,sexandcalendarperiod. expected survivalofmembersthegeneralpopulationmatched ratio oftheobservedsurvivalamongpatientswithcancerto tant formeasuringrelativesurvivalbecauseisa dents. Stableunderlyingorexpectedmortalityratesareimpor rates inthecensuscohortweremorestableforMétisrespon tables toages4590becausewithinthisagespan,mortality command inStataversion13(StataCorpLP).Werestrictedthelife using flexibleparametricmodelsimplementedwiththestpm2 calendar time–specificlifetablescreatedfromthecohortatlarge The excess mortality rate ratio comparing survival among Métis The excessmortality rate ratiocomparingsurvivalamongMétis For allcancersandbothsexescombined,cancerincidence year excess mortality rate ratios with 2 flexible We produced 5-year excess mortalityrate ratios with 2 flexible 24 Werestrictedtheseage-standardizedsur CMAJ | - MARCH 19,2018 , age - , sex - and | VOLUME 190 Table 1:Demographic characteristics of cohort members New Brunswick, Nova Brunswick, New Scotia, Prince Edward Island,andNewfoundland andLabrador. †“North” consists ofYukon, Northwest Territories “Atlantic” andNunavut; consists of from therounded data, sothosefor agiven variable maynot sumto 100%. totals andsubtotals are rounded independently. Similarly, percentages are calculated summed orgrouped, thetotal value maynot match theindividualvalues because randomly rounded such,whendata eitherupordown to amultiple of5.As are *According to Statistics Canadaprotocols, thecounts inthistable, includingtotals, are Characteristic 25–34 Age at cohort entry, yr Men Women Sex 35–44 45–54 65–74 55–64 North Region of residence† 75–99 British Columbia Saskatchewan Alberta Ontario Manitoba No highschool Highest level of schooling Atlantic Quebec trades certificate High school,withorwithout (non-university) Postsecondary University degree 1 (lowest) Income quintile 2 3 4 5 (highest) Rural Rurality Urban | ISSUE 11 Non-Aboriginal 1 320545(49.8) 1 332225(50.2) 2 052055(77.4) 738 335(27.8) 695 985(26.2) 456 715(17.2) 268 165(10.1) 344 905(13.0) 315 290(11.9) 982 175(37.0) 907 200(34.2) 687 485(25.9) 968 885(36.5) 413 065(15.6) 363 620(13.7) 439 965(16.6) 510 690(19.3) 550 505(20.8) 570 155(21.5) 581 450(21.9) 600 715(22.6) n =2652770 148 665(5.6) 236 200(8.9) 105 085(4.0) 218 875(8.3) 15 080(0.6) 92 580(3.5) no. (%)of respondents* Ethnic group; 5545 (50.2) 5505 (49.8) 4405 (39.9) 3110 (28.1) 1740 (15.7) 2595 (23.5) 2605 (23.6) 2330 (21.1) 5885 (53.3) 3645 (33.0) 1150 (10.4) 3425 (31.0) 2540 (23.0) 2100 (19.0) 1815 (16.4) 1170 (10.6) 5055 (45.7) 5995 (54.3) n =11050 1020 (9.2) 1005 (9.1) 260 (2.4) 515 (4.7) 785 (7.1) 665 (6.0) 230 (2.1) 835 (7.6) 370 (3.3) Métis RESEARCH E323 Model 2¶ 1.34 (1.18–1.52) 1.22 (1.03–1.43) 1.56 (1.28–1.89) 1.18 (1.02–1.37) 1.00 (0.86–1.17) 1.05 (0.99–1.11) 0.97 (0.89–1.06) 1.13 (1.04–1.24) 0.90 (0.75–1.06) 1.03 (0.83–1.26) 0.69 (0.50–0.95) 0.86 (0.66–1.13) 1.23 (0.91–1.67) 1.37 (0.98–1.90) 0.79 (0.56–1.10) 0.88 (0.61–1.27) 1.03 (0.70–1.51) 0.91 (0.64–1.32) 1.84 (1.23–2.76) 1.41 (0.96–2.08) 2.09 (1.30–3.38) 1.60 (1.03–2.48) 0.76 (0.47–1.24) 0.54 (0.35–0.84) 0.57 (0.31–1.06) 0.59 (0.37–0.94) 2.35 (1.12–4.96) Model no.; RR (95% CI) Model no.; Model 1§ 1.50 (1.32–1.70) 1.39 (1.18–1.64) 1.67 (1.38–2.03) 1.12 (0.97–1.30) 0.96 (0.82–1.11) 1.06 (1.00–1.12) 0.99 (0.91–1.07) 1.14 (1.04–1.24) 0.90 (0.76–1.08) 1.02 (0.83–1.26) 0.71 (0.52–0.97) 0.85 (0.65–1.12) 1.26 (0.93–1.71) 1.44 (1.04–2.01) 0.80 (0.57–1.11) 0.98 (0.68–1.41) 1.04 (0.71–1.53) 0.89 (0.62–1.28) 2.05 (1.37–3.06) 1.38 (0.94–2.03) 2.01 (1.25–3.25) 1.82 (1.17–2.83) 0.69 (0.42–1.13) 0.49 (0.32–0.76) 0.55 (0.30–1.03) 0.60 (0.34–0.96) 2.50 (1.19–5.27) ISSUE 11 ISSUE | 8.2 8.1 6.6 6.5 4.6 3.2 2.8 56.4 74.3 37.0 21.0 17.5 15.5 14.1 12.9 12.2 25.7 22.9 22.6 114.0 125.8 107.8 165.2 150.2 546.4 558.2 533.0 Métis dence was significantly higher for Métis women than for non- Aboriginal women. Métis had higher incidence rates for lung cancer in men and women separately; for larynx, liver and gall bladder cancers in both sexes combined; and for certain cancers incidence the cervix); (breast, system reproductive female the of sta not was result this but ovary, for higher numerically was rate inci lower had adults Métis Conversely, significant. tistically dence of colorectal cancer (women only) and of melanoma and leukemia for both sexes combined. VOLUME 190 VOLUME | 3.7 4.2 8.5 7.4 1.3 89.8 63.9 73.3 57.5 75.4 50.3 26.1 13.9 10.8 16.9 11.9 11.6 28.4 11.0 16.5 10.3 16.8 146.0 157.3 514.3 560.7 457.4 Ethnic group; ASR‡ per 100 000 ASR‡ group; Ethnic Non-Aboriginal MARCH 19, 2018 | CMAJ 23 5 5 95 75 35 40 35 30 30 25 25 25 25 25 15 15 15 10 10 125 165 145 115 570 525 225 1090 in Métis† No. of cases cases of No. standardized rate, CI = confidence interval, CNS = central nervous system, RR = relative risk. RR = relative nervous system, CNS = central interval, CI = confidence rate, -standardized §With adjustment for age and sex (if applicable) only. only. (if applicable) and sex age for §With adjustment and rurality. income (if applicable), sex age, for ¶With adjustment of the lung and bronchus. cancers = cancer **Lung Note: ASR = age Note: colorectal). prostate, breast, (lung, female sites 4 incident cancer and the top all sites for sex by *Breakdown the summed or grouped, are a multiple of 5. When data to either up or down rounded randomly are including totals, in this table, counts the Canada protocols, Statistics to †According independently. rounded are and subtotals totals because the individual values match may not value total Population. the World Standard to ‡Standardized Men Women breast Female Prostate Colorectal Cancer site Cancer Table 2: Age-standardized cancer incidence and relative risk of cancer among Métis and non-Aboriginal adults, 1992–2009, by by 1992–2009, adults, and non-Aboriginal among Métis cancer risk of relative and incidence cancer 2: Age-standardized Table Canada site, cancer and sex* All sites Men Women Lung** Men Women Non-Hodgkin lymphoma Kidney Stomach Bladder Oral and pharynxOral Pancreas Uterus Cervix Ovary Liver Larynx Thyroid Melanoma and CNS Brain Leukemia Gallbladder

In this study, for all cancers and both sexes combined, cancer In this study, for all cancers and both sexes combined, cancer incidence was not significantly different between Métis and non- differ not did also incidence -cancer all adults; Aboriginal between Métis and non-Aboriginal men. However, cancer inci Interpretation breast (female), colorectal and prostate cancers, but the differencethe but cancers, prostate and colorectal (female), breast was statistically significant only for prostate cancer (Table 3). RESEARCH other cancersinMétisadults.Thehigherincidenceofcervical may explain, in part, the high incidence of lung, breast and certain E324 associated withanincreasedriskofseveralcancertypes and obesityamongMétisishigh. Prostate Breast Lung†† ††Lung cancer =cancers ofthelungandbronchus. **Adjusted for age, sex (ifapplicable), timeperiod,income quintileandrurality. ¶Adjusted for age, sex (ifapplicable) andtimeperiod. §Age ‡Diagnosis between Jan.1,2001,andDec.31,2009. total value maynot match theindividualvalues because totals andsubtotals are rounded independently. †According to Statistics Canadaprotocols, thecounts inthistable, includingtotals, are randomly rounded either upordown to amultipleof5. Whendata are summed orgrouped, the *Diagnosis between Jan.1,1992,andDec.31,2009. Note: CI=confidence interval, EMRR=excess mortality rate ratio, NA=not applicable. Colorectal site Cancer non-Aboriginal adults aged 45–90at diagnosis, Canadaexcluding Quebec Table 3:Age-standardized 5-year relative survival by sex andethnicity, andexcess mortality rate ratios for Métis and Recent evidenceshowstheprevalenceofcigarettesmoking -standardized to International Cancer Standards. Survival cancers in Métis*† No. of 135 130 190 90 clarity ofpresentation. Aboriginal adultswerenarrowerthanthedatapointsinallregionsandthereforeomittedfor bronchus. Errorbarsindicate95%confidenceintervalsforMétisadults.non- by regionofresidence,bothsexescombined,1992–2009.Lungcancer=cancersthelungand Figure 1:Age-standardizedincidenceratesforlungcanceramongMétisandnonAboriginaladults, Sex andethnic group; age-standardized 5-yrrelative survival, %(95%CI)‡§ Non-Aboriginal 87.0 (86.0–88.0) 20.1 (19.1–21.1) 62.6 (61.2–64.0) NA Age-standardized lung cancer incidence rate, 2,25 per 100 000 person-years These 2factorsarestrongly Women 10 15 20 25 CMAJ 50 0 0 0 0 0 79.6 (68.0–93.2) 15.0 (10.0–22.6) 56.3 (43.2–73.4) 24 TotalR | MARCH 19,2018 Métis

NA Canada egion ofresidence(1991long-formcensus 26–28 Alberta and and Non-Aboriginal Métis 93.2 (92.5–93.9) 12.8 (12.1–13.6) 64.1 (62.9–65.4) |

VOLUME 190 Saskatchewan NA non vical screeningparticipationratesaresimilarbetweenMétisand tion, thoughlimitedevidenceinmorerecentyearssuggestscer cancer inMétiswomenmayberelatedtolowscreeningparticipa Métis people with breast, colorectal and prostate cancer, but the Métis peoplewithbreast,colorectalandprostatecancer,butthe non-Aboriginal - Aboriginal women. Manitoba Men 78.2 (65.4–93.4) 55.1 (65.4–93.4) | 9.1 (5.4–15.2) ISSUE 11 Ontario/Quebec Métis NA

All other regions ) 2,29 Survival was numerically lower for 1.03 (0.88–1.22) 3.58 (2.04–6.30) 1.61 (0.99–2.62) 1.14 (0.79–1.64) Model 1¶ EMRR (95%CI)* 1.00 (0.85–1.18) 2.60 (1.52–4.46) 1.43 (0.88–2.34) 1.14 (0.79–1.64) Model 2** RESEARCH

E325 Health Health 2011. accessed 51. (accessed (accessed Available: ( 31- 2016. 20(4): Cat no 82-624-X. 2009; accessed 2016 Mar. 3). 43. Int J Circumpolar Health Int J Circumpolar 2013. Cancer incidence and mor and incidence Cancer et al. et Health Rep S, Data resource profile: 1991 Canadian The Canadian census mortality follow- Mortality of Métis and registered Indian Cancer and related health care utilizationcare health related and Cancer Cancer risk factors and screening in the Cancer risk factors and screening in the Parker et al. Cancer in the Métis Nation of Ontario: clinical et al. et al. A, LD. , et al. R, L. C, S , S Cat no 99-011-X. https://www12.statcan.gc.ca/ Planning without facts: Ontario’s Aboriginal health Marrett Wilkins Marrett , Remaining life expectancy at age 25 and probability of Remaining life expectancy at age 25 and probability of Carter Mustard Senécal A , ME. , A, Colquhoun M, J R. R M, Available: Hill DC, M, Wilkins 2016. Amartey Wilkins ISSUE 11 ISSUE , Sanguins Kewayosh | Tjepkema Review of research on aboriginal populations in Canada: relevance M, Katt M Tjepkema DR, D, JG, B, R, PA, TK. Young up study, 1991 through 2001. Health Rep 2008;19(3):25- to their health needs. BMJ 2003;327:419-22. Withrow in the Manitoba Metis population. Winnipeg: Manitoba Metis Federation; Sanchez-Ramirez nhs-enm/2011/as-sa/99-011-x/99-011-x2011001-eng.cfm ( Rep 2011;22(4):31-6. Minore information challenge. J Agromedicine 2009;14:90-6. The Métis Nation. Ottawa: Métis National Council. Available: www.metisnation. ca/index.php/who-are-the-metis (accessed 2017 May 21). Aboriginal peoples in Canada: First Nations people, Métis and Inuit. Ottawa: Statis tics Canada; tality among the Metis population of Alberta, Canada. 2016;75:30059. Wilkins survival to age 75, by socio-economic status and Aboriginal ancestry. Tjepkema significance report. Ottawa: Métis Nation of Ontario; 2012. Bartlett adults in Canada: an 11-year follow-up study. Peters Health at a glance: select health indicators of First Nations people living off-reserve,living people Nations First of indicators health select glance: a at Health Métis and Inuit, 2007–2010. Ottawa: Statistics Canada; Constitution Part II (section 35): Rights of the aboriginal peoples of Canada. In: Act, 1982, being Schedule B to the Canada Act 1982, 1982, c. 11 (UK). Withrow Chronic Dis Inj Can 2014;34:103-12. Tjepkema off-reserve First Nations, Métis and non-Aboriginal populations of Ontario. Canadian Mortality Database. In: Microdata linkage program. Ottawa: Statistics Canada; 2017. Available: www.statcan.gc.ca/eng/health/link#cmdb 2018 Feb. 6). Canadian Cancer Registry (CCR). Ottawa: Statistics Canada; www23.statcan.gc.ca/imdb/p2SV.pl?Function=getSurvey&SDDS=3207 census cohort. Int J Epidemiol 2013;42:1319-26. 2016 Dec. 28).

. 9. 6. 7. 8. 5. 1. 2. 4. 3

10. 12. 13. 11. 14. References Conclusion public evidence to support of this work is in providing The value to that can ultimately contribute health policy and programming and burden of cancer and other chronic dis a reduction in the risk people of Canada. System-level efforts, eases among the Métis and empha risk-reduction strategies with culturally appropriate and cessation and healthy weights, sizing tobacco prevention to reduce the high burden of potentially could be considered the higher incidence of cervicalavoidable cancers. Furthermore, in women suggests that improvements cancer among Métis benefits. The poorer survival of Métis screening would yield cancer requires further research to identifypatients with prostate and, where appropriate, potential the causes of the disparity of cancer riskactions to reduce them. Our limited understanding stems from a lackand burden in Aboriginal populations in Canada The develop of ethnic identifiers in Canadian health databases. systems that include ment of more comprehensive information and evaluate strategiesethnic identifiers will be crucial to inform and the rest of the to reduce health disparities between Métis Canadian population. taking into account potential differences between rural and and rural between differences potential into account taking the cannot definitively conclude As a result, we remote areas. by these factors. residual confounding absence of 16. 15. VOLUME 190 VOLUME |

4 In 10–12 did not did not 4 = 2551 cancers MARCH 19, 2018

| 33 CMAJ Finally, Tjepkema and colleagues 12 However, the ideal classification of Métis However, the ideal classification of Métis = 168 cancers among Métis participants dur = 168 cancers among 30–32 The Manitoba study was larger (n The Manitoba study was 10 = 444 cancers among Métis participants during Métis participants during = 444 cancers among Unlike our results, Manitoba Métis women did not not did women Métis Manitoba results, our Unlike 11 Although our cohort began in 1991, it provides important Although our cohort began in 1991, it provides important Only 3 studies, all at the provincial level, have previously level, have previously all at the provincial Only 3 studies, Ontario, researchers found no difference between Métis and all all and Métis between difference no found researchers Ontario, a suggestion of lower overall incidence Ontarians, except for however, the numbers were too small among Métis participants; to be informative (n ing 2005–2007). among Métis participants during 1998–2007) and, as in our during 1998–2007) and, as in our among Métis participants incidence among Métis and all Manito study, showed similar and for colorectal and prostate can bans for all sites combined of lung cancer for Métis males and cers, with higher rates females. information for planning and prevention efforts. A more recent information for planning and prevention efforts. A more recent cohort would not have allowed sufficient power to measure can cer burden among Métis participants. Our cohort had sufficient follow-up, with more than 18 years of combined data; however, we were still limited by a relatively small sample, which was too not did sources data Our time. over trends explore to small include stage of diagnosis or lifestyle risk factors, and we were consequently unable to explore the role of these factors in the observed disparities. Income was measured at the aggregate not dichotomized, was rurality and level, than individual) (rather

Strengths and limitations Using census data This study had both strengths and limitations. to self-reported allowed for the identification of Métis according derived from ancestry, which is preferable to ethnic identifiers often based on sub the medical record, given that the latter are jective appraisal. result was statistically significant only for prostate cancer. Con cancer. for prostate only significant was statistically result disparitiesthe explain to little did rurality and income for trolling the populations. or survival between in incidence in the Métis population. cancer incidence examined would be based on self-identity, which was not requested in the 1991 census. The generalizability of data from Métis participants as defined in this cohort to the Métis people of today is unclear. The estimated size of the Métis population has increased since 1991 because of both natural growth and changes in the likeli hood of reporting Métis identity on the census. looked at mortality among Métis people in Canada using the in Canada using the looked at mortality among Métis people As in our study of 1991 census cohort followed through 2001. all-cancer mortal cancer incidence, those authors found similar women, higher lung ity rates in men but a higher rate in Métis colorectal cancer cancer mortality in Métis women and similar sexes, relative to non- mortality rates for Métis people of both elevated lung cancer Aboriginal Canadians. Whereas we found colleagues incidence among Métis men, Tjepkema and 2007–2012), researchers reported results that were qualitatively that were qualitatively 2007–2012), researchers reported results and for lung, breast, similar to ours for all cancers combined statistical significance prostate and colorectal cancers, although sexes combined and was lacking except for lung cancer (both than Métis for higher significantly were rates which for males), for non-Métis Albertans. experience significantly higher rates of breast or cervical cancer. higher rates of breast or cervical cancer. experience significantly In Alberta (n report higher lung cancer–specific mortality. report higher lung cancer–specific mortality. RESEARCH 25. 24. 23. 22. 21. 20. 19. E326 18. 17. Tjepkema and Loraine Marrett conceptualized Tjepkema andLoraineMarrettconceptualized Contributors: National Council(Vides),Ottawa,Ont. sion (Tjepkema),StatisticsCanada;Métis Toronto, Ont.;HealthAnalysisDivi Health (Withrow,Marrett),Universityof Care Ontario;DallaLanaSchoolofPublic (Mazereeuw, Withrow,Nishri,Marrett),Cancer Affiliations: PreventionandCancerControl This articlehasbeenpeerreviewed. Competing interests:Nonedeclared. Gionet age standardisingsurvivalratios.EurJCancer2004;40:2307-16. off reserve,MétisandInuit.Ottawa:StatisticsCanada;2013Catno82-624X. Corazziari national AgencyforResearchonCancer; Cancer incidenceinfivecontinents.Vol6.IARCSciPubl120.Lyon(France):Inter Chapter 7:Agestandardization.In:Parkin Anal Bull2001;3(3):1-17.StatisticsCanadaCatno21006XIE. du Plessis 1991 censusdictionary.Ottawa:StatisticsCanada;1992Catno92-301E. (accessed 2015July27). Institute; Site recode ICD third edition).EurJCancerPrev2005;14:307-8. Working GroupReport. 13(1): survival fromprostate,breast,colorectalandlungcancer. Ellison adian CancerSociety;2014. Canadian cancerstatistics2014—specialtopic:skincancers.Toronto:Can 23- LF, L, 34. Roshanafshar 2003. Gibbons V, I , Quinn Beshiri Available: -O Diana Withrow, Michael -3 (1/27/2003) definition. Bethesda (MD): National Cancer L M ; R, Canadian CancerSurvivalAnalysisGroup. , Capocaccia Bollman International rulesformultipleprimarycancers(ICD-0 S. http://seer.cancer.gov/siterecode/icdo3_d01272003 Select healthindicatorsofFirstNationspeopleliving RD. R Definitions ofrural.Rural Small Town Can . Standard cancerpatientpopulationfor 1992:112-115. DM, Muir CMAJ CS, Whelan tical analysis. Eduardo Vides provided content tical analysis.Eduardo Vides provided content subject matterexpertiseandguidedthestatis Loraine Marrettprovidedmethodologicand analysis. DianeNishri,MichaelTjepkemaand eeuw and DianaWithrow performed the data and implementedthestudy.MaeganMazer final approval of the version to be published final approvaloftheversiontobepublished intellectual content.Alloftheauthorsgave authors criticallyrevieweditforimportant Mazereeuw draftedthearticle,andallof perspective oftheMétisNation.Maegan expertise anddatainterpretationfromthe | MARCH 19,2018 Health Rep SL, year relative Five-year relative et al., editors. editors. 2001;

| VOLUME 190 32. 31. 30. 33. 26. 28. 27. 29. Clegg Torres StraitIslanders.AustCollMidwivesIncJ1995;8(3):26-9. Robertson 2003;93:1685-8. collection of data on race, ethnicity, and birthplace. Gomez Health Policy; utilization in Manitoba:a population-based study. Winnipeg:ManitobaCentrefor lations: problems,optionsandimplications.CanStudPopul2004;31:55-82. Guimond based study. ties: a SEER (Surveillance, Epidemiology, and End Results) Program population- and environmentalfactorsintheUK2010. Parkin Cogliano Washington: AmericanInstituteforCancerResearch;2007. nutrition, physical activity and the prevention of cancer: a global perspective. World CancerResearchFund/AmericanInstitutefor. Martens human cancers.JNatlCancerInst2011;103:1827-39. LX, DM, SL, P Li E , VJ, Bartlett , H, Boyd | Le FP, Kerr ISSUE 11 Arch InternMed Lumley Baan 2010. GM, Hankey D L , , J West Beaujot Walker R , Burland , J, Straif [email protected] Correspondence to:MaeganMazereeuw, Accepted: Sept.12,2017 cohort.” in Canada: follow- and survivalinFirstNationsMétisadults Operating Grantentitled“Cancerincidence adian InstitutesofHealthResearchOpen Funding: TheworkwassupportedbyaCan of thework. and agreedtobeaccountableforallaspects BF, Berg DW, LC. R et al. 2002; . K S. E et al. Charting thegrowthofCanada’sAboriginalpopu , 16. The fraction of cancer attributable to lifestyle 16. Thefractionofcancerattributabletolifestyle , et al. How midwivesidentifywomenasaboriginalor et al. Cancer survival among US whites andminori 162: Hospital policyandpracticeregardingthe Profile of Metis health status and healthcare Profile ofMetishealthstatusandhealthcare Preventable exposuresassociatedwith 1985- Br JCancer 93. up of the 1991 census 2011;

Am JPublicHealth 105( Suppl 2):S77- Food, 81.