Chapter 7 The epidemiology of solar radiation and skin cancer

This chapter reviews the history of and epidemiological evidence on the relationship between sun exposure and skin cancer and, in doing so, addresses the three most frequent types of skin cancer, basal cell (BCC) and squamous cell (SCC) carcinomas and melanoma, individually. There is persuasive evidence that BCC, SCC and melanoma are caused by sun exposure with the higher rates in fairer, sun-sensitive than in darker-skinned, less sun-sensitive people, with increasing risk with increasing ambient solar radiation, highest densities on the most sun exposed and lowest on the unexposed parts of the body, and with associations in individuals with total (mainly SCC), occupational (mainly SCC) and non-occupational or recreational sun exposure (mainly melanoma and BCC) and a history of sunburn and presence of benign sun damage in the skin. Sun protection is essential if skin cancer incidence is to be reduced. The epidemiological data suggest that in implementing sun protection an increase in intermittency of exposure should be avoided, that sun protection will have the greatest impact if achieved as early as possible in life, and that it will probably have an impact later in life, especially in those who had high childhood exposure to solar radiation. Rigorous epidemiological testing of the hypotheses underlying these suggestions would be desirable but challenging.