Possible reasons for this increase include extended recreational exposure to the sun, thinning of the ozone layer, allowing more harmful rays to reach the earth's surface and better detection of the disease. The number of deaths from melanoma is not rising rapidly, probably due to earlier detection and treatment. Since 1960, more of the melanomas diagnosed have been localized. This means they show no evidence of metastasis and have a greater potential for cure. People who have had three or more severe sunburns as a child or adolescent are at greater risk for developing melanoma.
Skin cancer is more common among people with lightly pigmented skin.
Exposure to sunlight is likely to be harmful, particularly if it results in sunburn. Skin cancer incidence rates for whites are more than ten times higher than the rates for blacks. Many light-skinned people have a large number of moles and this seems to be an indicator of increased risk. This is particularly true if the moles are dysplastic or atypical in appearance. In the early stages, melanoma usually has no symptoms but can be detected as a small area of abnormal pigmentation of the skin.