Stage of diagnosis and survival for prostate cancer among immigrant men in Ontario, Canada.

INTRODUCTION: We previously identified specific immigrant groups (West African and Caribbean) with increased incidence of prostate cancer in Ontario, Canada. In this population-level retrospective cohort study, we used administrative databases to compare stage of diagnosis, 5-year overall survival and prostate cancer-specific survival for immigrants versus long-term residents of Ontario.

METHODS: We linked several provincial-level databases available at ICES, an independent, non-profit research institute. We included all male Ontario residents 20-105 years of age who had an incident prostate cancer diagnosis date between March 31, 2008 and March 31, 2017, stratified into immigrants vs. long-term residents. We used multivariable logistic regression to determine the odds of early (stage I-II) vs. late (III-IV) stage of diagnosis, adjusting for age, co-morbidities, neighbourhood income and continuity of care. We produced Kaplan-Meier curves for 5-year overall survival and for 5-year prostate cancer-specific survival.

RESULTS: Compared to long-term residents, men from West Africa (adjusted odds ratio 1.66 [95% CI 1.16-2.38], East Africa (AOR 1.54 [95% CI 1.02-2.33]) and the Caribbean (AOR 1.22 [95% CI 1.01-1.47]) had a diagnostic stage advantage, and men from South Asia were most likely to be diagnosed at a late stage. In both unadjusted and adjusted analyses, overall and prostate cancer-specific survival were higher for immigrants than long-term residents. The highest five-year overall survival was seen for men from Sub-Saharan Africa and the Caribbean, and the lowest was seen for South Asian men, where 11.7% died within five years of diagnosis.

CONCLUSION: Immigrant men in Ontario with prostate cancer are more likely to be diagnosed at an early stage and to survive for 5 years than long-term residents. Among immigrant men, men from the Caribbean and Sub-Saharan Africa have the greatest stage and survival advantage and South Asian men the least. Differences in awareness, diagnostic suspicion, genetic predisposition, and social factors may play a role in these findings.