Exposure to solar ultraviolet radiation is the major cause of most skin cancers

Overexposure to UVR can lead to sun burn, immunological changes, precipitation or exacerbation of photosensitivity, accelerated skin aging, and skin cancer. An association between sunlight and skin cancer was first noted in the late 1800's when the increased cancer susceptibility of fair skinned individuals exposed to a large amount of sunlight was documented. The incidence of skin cancer has been increasing rapidly in recent years, and this has been attributed to depletion of the ozone layer and an increased frequency of recreational activities involving exposure to the solar rays. Exposure to UV light is considered to be a major risk factor for the development of squamous cell carcinoma (SCC), basal cell carcinoma (BCC), and melanoma. Alterations in the p53 tumor suppressor gene have been detected at a relatively high frequency in human skin tumors (=50% for SCC and BCC). The base changes observed inp53 from these tumors are similar to those induced in model systems by UV light, implying that this agent is responsible for the mutations. One of the cellular targets for sunlight induced damage is DNA.