Overview of ultraviolet radiation and cancer: what is the link? How are we doing?

Sun exposure has now been established as the most important avoidable cause of nonmelanoma skin cancer (NMSC) and melanoma. With specific reference to melanoma, there are several key issues that remain to be resolved. These include definition of the action spectrum, the importance of systemic effects of sun exposure, whether a tan is protective, the risk of tanning booth exposures, and the efficacy of sunscreens. Also the role, if any, of sun exposure in noncutaneous malignancies remains to be established. Melanoma incidence and mortality have increased dramatically over the past several decades, but these increases have now slowed, and for mortality among those 15 to 45 years of age, decreasing rates are now observed. Improving the coverage of the Surveillance, Epidemiology, and End Results (SEER) registries by requiring pathology laboratories in non-SEER areas to report cancers among SEER area residents will allow correct interpretation of these trends in the future at minimal cost. The available data on trends in NMSC incidence and mortality are suboptimal but suggest a pattern of declining mortality despite increasing incidence. Trends in NMSC morbidity have not been defined. Establishing NMSC registries in a few diverse sentinel areas would allow more reliable inference and monitoring. Techniques are being developed for reducing sun exposures and increasing early detection of skin cancers in the general population, but improved monitoring of incidence, mortality, and morbidity is required to monitor the effects of current and future ozone depletion and to evaluate prevention and early detection measures.