Cancer incidence in Asian migrants to New South Wales, Australia.

Cancer incidence during 1972-90 in Asian migrants to New South Wales, Australia, is described. Overall cancer incidence was lower than in the Australia born in most migrant groups, and this reached significance in migrants born in China/Taiwan, the Philippines, Vietnam and India/Sri Lanka, and in male migrants born in Indonesia. For the majority of cancers, rates were more similar to those in the Australia born than to those in the countries of birth. For cancers of the breast, colorectum and prostate, rates were relatively low in the countries of birth, but migrants generally exhibited rates nearer those of the Australia born. For cancers of the liver and cervix and, in India/Sri Lanka-born migrants, of the oral cavity, incidence was relatively high in the countries of birth but tended to be lower, nearer Australia-born rates, in the migrants. For these cancers, environmental factors related to the migrant's adopted country, and migrant selection, appeared to have a major effect on the risk of cancer. For certain other cancers, incidence was more similar to that in the countries of birth. Nasopharyngeal cancer, and lung cancer in females, had high rates in both the countries of birth and in migrants to Australia. Nasopharyngeal cancer rates were highest in China/Taiwan and Hong Kong-born migrants, and were also significantly high in migrants from Malaysia/Singapore, Vietnam and the Philippines. Rates of lung cancer were significantly high in women born in China/Taiwan, and the excess was greater for adenocarcinoma than for squamous cell carcinoma. Melanoma had low rates in both the migrants and in the countries of birth. For these cancers, it was probable that genetic factors, or environmental factors acting prior to migration, were important in causation.