Cancer incidence patterns among Chinese immigrant populations in Alberta

This study examines the incidence of cancer among Chinese immigrants to Alberta in comparison to the incidence in Canadian-born Alberta residents and in people of Chinese origin still living in China. Cancer cases among Chinese immigrants and Canadian-born Alberta residents were identified from the Alberta Cancer Registry (1974-1993). Incidence rates for Shanghai (1975-1992) were obtained from the International Agency for Research on Cancer (IARC) publications. Direct age-standardized incidence rates (ASIRs) were calculated using the "world standard population." Descriptive analysis and Poisson regression modelling were employed to obtain the rate ratios for certain cancer sites among the three populations. For males, the overall incidence of cancer (excluding non-melanoma skin cancer) was lowest in Chinese immigrants while being similar in Canadian-born Alberta residents and Chinese living in Shanghai (197 vs. 224 and 232/100,000). For females, the overall incidence in Chinese immigrants was lower than Canadian-born Alberta residents but similar to that in Chinese living in Shanghai (154 vs 200 and 150/100,000). For cancers that are common in China (stomach and esophagus), the incidence rates for Chinese immigrants were more similar to those for Canadian-born residents than to rates for Shanghai. However, the incidence of liver cancer was very high in the immigrants, suggesting the possible presence of an initiating event during childhood or early adulthood. For cancers that are traditionally uncommon in China (breast and prostate), rates for immigrants were mid-way between those of the two comparison groups. This study supports observations that the risk of cancer in immigrants tends towards the risk of people in the new host country.