Site-Specific Cancer Incidence by Race and Immigration Status in Canada 2006-2015: A Population-Based Data Linkage Study

Abstract

Background: The Canadian Cancer Registry (CCR) does not collect demographic data beyond age and sex, making it difficult to monitor health inequalities. Using data linkage, we compared site-specific cancer incidence rates by race.

Methods: The 2006 and 2011 Canadian Census Health and Environment Cohorts are population-based probabilistically linked datasets of 5.9 million respondents of the 2006 long-form census and 6.5 million respondents of the 2011 National Household Survey. Race was self-reported. Respondent data were linked with the CCR up to 2015. We calculated age-standardized incidence rate ratios (ASIRR), comparing group-specific rates to the overall population rate with bootstrapped 95% confidence intervals (CI). We used negative binomial regressions to adjust for socioeconomic variables and assess interactions with immigration status.

Results: The age-standardized overall cancer incidence rate was lower in almost all non-White racial groups than in the overall population, except for White and Indigenous peoples who had higher incidence rates than the overall population (ASIRRs, 1.03-1.04). Immigrants had substantially lower age-standardized overall cancer incidence rates than nonimmigrants (ASIRR, 0.83; 95% CI, 0.82-0.84). Stomach, liver, and thyroid cancers and multiple myelomas were the sites where non-White racial groups had consistently higher site-specific cancer incidence rates than the overall population. Immigration status was an important modifier of cancer risk in the interaction model.

Conclusions: Differences in cancer incidence between racial groups are likely influenced by differences in lifestyles, early life exposures, and selection factors for immigration.

Impact: Data linkage can help monitor health inequalities and assess progress in preventive interventions against cancer. See related commentary by Withrow and Gomez, p. 876.