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

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.