Cancer mortality in migrant populations within Italy.

METHODS. Mortality rates for four types of cancer (stomach, colorectal, lung, and breast cancer) in migrant populations were compared to those of individuals who still resided in the political region in which they were born. The effects on mortality rates of place of birth and of place of residence were studied, comparing different regression models. RESULTS. Overall, people who were born in the South and who later migrated had significantly higher mortality rates than the southern population, but lower than the population in the area of residence, for most cancers. Place of birth and place of residence showed different power in explaining the observed mortality rates for different cancer sites: place of birth was a stronger predictor for stomach and breast cancers, while residence was a stronger predictor for lung and colorectal cancers. The status of 'migrant' was found to be an overall risk factor. The compatibility of the results obtained with different aetiological hypotheses is discussed.