Melanoma is the most serious form of skin cancer. Even so, if diagnosed and removed while it is still thin and limited to the outermost skin layer, it is almost 100% curable. Once the cancer advances and metastasizes (spreads) to other parts of the body, it is hard to treat and can be deadly. During the past 10 years the number of cases of melanoma has increased more rapidly than that of any other cancer. Over 51,000 new cases are reported to the American Cancer Society each year, and it is probable that a great many more occur and are not reported.