The disparities in gastrointestinal cancer incidence among Chinese populations in Shanghai compared to Chinese immigrants and indigenous non-Hispanic white populations in Los Angeles, USA.

Gastrointestinal cancer patterns are distinct among populations. Our study aims to compare the incidence and risk of gastrointestinal cancers between Chinese American and non-Hispanic whites in Los Angeles, CA, USA, to those of people indigenous to Shanghai to elucidate the changing patterns of gastrointestinal cancers. Cancer incidence data from 1988 to 2012 were extracted from the Cancer Incidence in Five Continents plus database. The age standardized incidence and estimated annual percentage change were calculated to estimate the temporal trends of gastrointestinal cancers. Traditional Poisson regression models and three-factor constrained Poisson regression models were applied to compare the gastrointestinal cancer risk across populations. The incidences of oesophageal, stomach, liver and gall bladder cancers were higher among indigenous Chinese residents of Shanghai than among the other two populations in Los Angeles. While the incidences of colorectal and pancreatic cancer were higher among non-Hispanic whites, Chinese American immigrants were considered to be at an intermediate level for most gastrointestinal cancers. The gender-specific gastrointestinal cancer disparities across populations, especially between Shanghai Chinese and non-Hispanic US whites, were significant regardless of age, period or cohort scale. However, the regional differences in gastrointestinal cancer rates decreased over time. Most gastrointestinal cancer patterns in Chinese American immigrants were more aligned to those of their new country of residence than to those of their original country. The disparities in gastrointestinal cancers across populations indicate that environmental factors might play a key role in cancer genesis. Shift in environmental exposures may result in significant changes in gastrointestinal cancer incidence.