It's long been known that tanning is the body's attempt to shield itself from the sun. But researchers have only recently discovered that, paradoxically, these protective measures sometimes cause cancer. These repair efforts, however, can go awry and lead to cancer. Tanning occurs when the enzymes stimulate pigment cells in the upper layers of the skin to produce melanin, a black substance that absorbs ultraviolet light. Melanin's role is to protect the DNA in lower layers of skin cells.
Cancer is really a number of diseases caused by the abnormal growth of cells.
Even skin cancer is a general term for several different forms of the disease. Basal cell carcinoma, which usually affects the face and ears, causes about 75 percent of all skin tumors. It is slow-moving and does not generally spread to other parts of the body. Squamous cell carcinoma, responsible for about 20 percent of skin tumors, grows slowly too, but it does spread more often than basal cell cancer. Malignant melanoma is the most harmful because it can spread quickly and be fatal if it's not treated early.