Solar exposure in the etiology of cutaneous melanoma

Several lines of evidence suggest a role for solar exposure in the etiology of cutaneous melanoma. Increased incidence rates in light-complexioned, easily burning, poor tanning individuals; lower rates in Blacks and Orientals; higher rates geographically within countries as the equator is approached; and site differences by sex, which appear to be related to clothing differences, all support a role for solar exposure. Migration data and case control studies have emphasized the importance of intense exposures early in life rather than cumulative total lifetime exposure, which appears to be more important with the nonmelanoma forms of skin cancer. With the recognition of dysplastic nevi as precursors to melanoma, the causation of melanoma appears multifactored. The mechanisms by which sunlight may be involved in melanoma etiology are considered.