A role for photoproducts of vitamin D in the etiology of cutaneous melanoma?

Several clinical and epidemiological aspects of cutaneous melanoma seem anomalous because they contrast with other sunlight-associated skin cancers. For example, persons with the greatest risk of melanoma are not those with the greatest cumulative solar exposure, the anatomic areas that receive the most solar exposure are not preferentially affected, and the incidence of the disease is seasonal, with more cases reported in summer than winter. This article discusses the synthesis and biologic effects of vitamin D photoproducts and suggests that sun-related local skin effects, mediated by vitamin D photoproducts, on melanocytes previously damaged by excessive solar exposure may help explain the seemingly anomalous aspects of melanoma.