Migration and death from malignant melanoma.

The age-standardized mortality rates for malignant melanoma of the skin in immigrants to New Zealand were compared with those of New Zealand-born non-Maoris. Immigrants from European countries had mortality rates that were generally similar to those prevailing in their countries of origin, although, among immigrants from the British Isles, early age at migration was associated with a mortality rate similar to that of New Zealand-born non-Maoris. In a community survey, British immigrants were not less likely to have had severe sunburn, but had fewer moles, than New Zealand-born non-Maoris. The lower melanoma mortality, and the effect of age at migration, could be mediated by differences in mole frequency.