Abstract
OBJECTIVES: With increasing immigration in Canada and strained cancer treatment infrastructure, there's a pressing need for long-term data on immigrant health and cancer incidence. This information is crucial for planning future cancer services and to alleviate the burden on both the population and healthcare system. METHODS: Statistics Canada data were linked from the 1991 Canadian Census, Canadian Cancer Registry, and Canadian Vital Statistics Database to follow a cohort from 1992 to 2015 and compare cancer incidence between immigrants and the Canadian-born for any cancer and specific types of cancers. Immigrants were further classified based on time spent in Canada. RESULTS: Immigrants had lower odds of developing any cancer (OR = 0.92, 95% CI [0.92-0.93], p < 0.001) compared to non-immigrants. However, for stomach cancer and non-cervical gynecological cancers, the odds of cancer incidence were greater for immigrants than for the Canadian-born. Cox regression showed that recent immigrants (0-4 years in Canada) had a lower hazard ratio (HR = 0.77, 95% CI [0.71-0.84], p < 0.001) compared to non-immigrants. Those who lived 5-9 years and 10-19 years in Canada had a higher hazard ratio (HR = 0.82, 95% CI [0.75-0.89], p < 0.001; HR = 0.90, 95% CI [0.82-0.98], p = 0.011), respectively. Immigrants who had been in Canada for 20 years or longer had the highest hazard ratio (HR = 0.98, 95% CI [0.90-1.07], p = 0.632), indicating that the so-called "healthy immigrant effect" lessens over time. CONCLUSION: Results demonstrated the healthy immigrant effect lessens over time spent in Canada. However, this effect was not uniform across countries of origin and cancer types. Therefore, this research, provides a deeper understanding of immigrant cancer outcomes and will be useful for cancer planning services and cancer control strategies.