Time trends of incidence for cutaneous melanoma among the Japanese population: an analysis of Osaka Cancer Registry data, 1964-95.

Cutaneous malignant melanoma occurs much less frequently among non-white populations than among white populations. Little is known of the descriptive epidemiology of melanoma among Japanese. We investigated time trends of incidence of invasive cutaneous malignant melanoma using data from the Osaka Cancer Registry (Japan) among 321 men and 313 women diagnosed between 1964-95. Average, annual, age-standardized incidence rates per 1,000,000 population were 2.45 (95% confidence interval (CI): 2.17-2.72) for men and 2.04 (95% CI: 1.81-2.28) for women. The age-standardized rate ratio among men from 1964-71 as a reference was almost constant during the study period, whereas that among women increased up to 1.8 fold (95% CI: 1.25-2.56) in 1980-87 and seems to have reached a plateau recently. Among men, the ratio for head and neck lesions decreased to 0.5 fold (95% CI: 0.26-0.99) in 1988-95. Among women, the ratio for lesions of the extremities steeply increased up to 4.7 fold (95% CI: 2.68-8.35) in 1980-87 from the reference period of 1964-71, whereas a slight increase for trunk lesions and no increase for head and neck lesions were noted during the same period. Possible explanations for the subsite-specific time trends are discussed.