Skin melanoma and seasonal patterns.

While laboratory experiments have never proved that solar ultraviolet radiation (UV-B) causes skin melanoma, epidemiological research has strongly suggested that this is the case. Monthly patterns of the solar radiation which reaches the earth's surface show that the greatest intensities of UV-B occur during the summer months. This study uses first-order harmonics (sine curve models) to analyze the monthly incidence of skin melanoma in the United States and to test for seasonal patterns. The association between occurrence of melanoma and the degree of solar insolation may provide new insight into the mechanics of the biologic action spectrum and the dose-response relationships suspected for this disease. Does short term, high intensity UV-B promote tumor development? Using data from the Third National Cancer Survey (1969-1971), seasonal patterns for whites were studied in detail by anatomic site, sex, age and geographic region. Overall, a strong seasonal pattern with summertime peak was observed for females. This was most pronounced for women under age 55 years, and for women of all ages with melanomas of the upper and lower extremities. Among men, a seasonal pattern with summertime peak was observed only for melanomas of the upper extremities. From the data available, it is difficult to determine if the seasonal patterns of melanoma result from the promoting effects of UV-B exposure or from enhanced recognition during the summer months.