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

Abstract

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