Skin cancer is the world’s most common form of cancer. Like nearly all living tissue, the skin constantly forms new cells to replace worn ones. But some harmful factors—especially the sun’s rays—can damage the genes (hereditary material) in skin cells. When certain genes are damaged, cells can multiply wildly instead of dividing in their normal, orderly way. Cancer arises from this uncontrolled multiplication.
The best way to prevent skin cancer is to protect the skin from excess sun. Doctors believe that people could avoid many skin cancers with such measures as using sunscreen regularly and wearing protective clothing.
Doctors group skin cancer in two broad categories that reflect different levels of seriousness of the disease. The more serious category is a dangerous skin cancer called melanoma << mehl uh NOH muh >> . The other category—nonmelanoma skin cancer—is much easier to treat.
Melanoma
arises in melanocytes << MEHL uh nuh syts >> , the cells that make the pigment that gives skin its natural color. Some melanomas form in moles that change into cancer. Others begin to grow in skin with no previous markings. Melanoma is an extremely aggressive cancer that tends to spread to other parts of the body. But most melanomas that are detected early can be cured by removing the growth and a margin of healthy tissue.
Because early detection is so vital, doctors recommend that people learn the warning signs of melanoma and examine their skin regularly. Skin examination is especially important for people who have an increased risk of melanoma. Factors for increased risk include having light skin and green or blue eyes; having a large number of moles; and having already had a melanoma.
Doctors have developed a memory aid called ABCD to help people remember how to evaluate a pigmented area for danger signs of melanoma. In ABCD, A stands for a_symmetry–that is, the shape of one side is unlike the other side; _B stands for an irregular b_order; _C stands for variations in c_olor; and _D stands for _d_iameter greater than 6 millimeters (about the size of a pencil eraser). People should see a doctor immediately about an area that has any of these characteristics.
Nonmelanoma skin cancer
occurs in two principal forms—basal cell cancer and squamous cell cancer. Both of these cancers can have a wide variety of appearances, including small red or pearly bumps; flat, scaly, red areas; or sores that do not heal. Experts recommend that people consult a medical professional about any change in their skin that lasts longer than about three weeks.
Basal cell cancer is the most common nonmelanoma skin cancer. It rarely spreads beyond the skin. Squamous cell cancer is slightly more likely to spread than basal cell. Because they usually do not spread, most nonmelanoma cancers can be cured by removing the affected skin. Cancer that has spread is more difficult to cure. People who have had one nonmelanoma skin cancer have an increased risk of forming additional cancers in their skin and in their other organs. Anyone who has had skin cancer should have regular medical checkups.
