Individuals diagnosed with a first malignant melanoma of the skin have a significantly increased risk of being diagnosed with a second malignant melanoma, according to a report in the current issue of the International Journal of Cancer.

Malignant melanoma is a serious form of cancer that usually starts in the skin, either in a mole or in normal-looking skin. The incidence of this cancer is increasing. Most skin cancers occur on areas of the skin that are regularly exposed to sunlight or other ultraviolet radiation.

Dr. Fabio Levi, of Institut Universitaire de Medicine Sociale et Preventive, Lausanne, Switzerland, and colleagues examined the risk of a second primary malignant melanoma in patients treated for a first malignant melanoma using data from a population-based cohort of 3,439 patients diagnosed between 1974 and 2003.

A total of 43 cases of second malignant melanoma were observed - significantly more than the “expected number” of cases - about 9. Individuals 50 years of age or younger appeared most susceptible to a second malignant melanoma.

Of the 43 second malignant melanomas, 31 were at a different site than the first skin cancer and 12 were at the same site as the first cancer. The cumulative risk of second malignant melanoma at 20 years was roughly 5 percent.

These findings, conclude the researchers, clearly show that the risk of malignant melanoma of the skin is substantially increased in people with a history of this cancer.

SOURCE: International Journal of Cancer December 2005.