Trends in the incidence of malignant melanoma in Sweden, by anatomic site, 1960-1984.

This study was based on 15,376 patients in Sweden with cutaneous malignant melanoma diagnosed during the 25-year period 1960-1984. Trunk melanoma increased substantially during that period among men, with age-standardized rates rising from 1.1 to 7.0 per 10(5). Among women, the greatest increases occurred in melanoma of the upper extremity (rising from 0.4 to 2.3), lower extremity (rising from 1.6 to 4.4), and trunk (rising form 0.6 to 3.1), but the rates for the latter two sites seemed to level off after 1978. Multivariate analyses showed that models based on a common parameter ("drift"), including linear birth cohort and/or time periods effects, were significantly superior to simple age models for explaining incidence trends for each separate site. Further, in men with melanoma of the trunk and upper and lower extremities, birth cohort effects had significant effects compared with drift. In contrast, in women, time period effects were a significant improvement on drift for melanoma of the trunk and lower extremity. The relative risk of malignant melanoma among men leveled off in later-born cohorts for all separate sites. A similar trend was found in women, except for melanomas of the trunk, in which the increase in relative risk persisted. The results indicate sex-specific differences in temporal trends of exposure to factors causing malignant melanoma.