People with a family history of more than one melanoma skin cancers are more likely to develop multiple primary melanoma lesions themselves, according to an article in the October 5 issue of the Journal of the American Medical Association.

Cristina R. Ferrone, MD, and colleagues from Memorial Sloan-Kettering Cancer Center, New York, conducted a study to identify the incidence and characteristics of patients at risk of developing multiple primary melanomas. The study included 4,484 patients diagnosed with a first primary melanoma between January 1, 1996, and December 31, 2002.

The researchers found that 385 patients (8.6 percent) had 2 or more primary melanomas, with an average of 2.3 melanomas for each such patient. Over three quarters (78 percent) had 2 primary melanomas. For 74 percent of patients, the initial melanoma was the thickest tumor.

Fully 59 percent presented with a second primary tumor within 1 year; 21 percent of multiple primary lesion patients had a positive family history of melanoma compared with only 12 percent of patients with a single primary melanoma. In addition, 38 percent of multiple primary lesion patients had dysplastic nevi compared with 18 percent of single primary lesion patients.

The estimated cumulative 5-year risk of a second primary tumor for the entire cohort was 11.4 percent, with almost half of that risk occurring within the first year. For patients with a positive family history or dysplastic nevi, the estimated 5-year risk of multiple melanomas was significantly higher at 19.1 percent and 23.7 percent, respectively.

The most striking increase in incidence for the multiple primary lesion population was seen for development of a third primary melanoma from the time of second primary melanoma, which was 15.6 percent at 1 year and 30.9 percent at 5 years.

"Patients with a positive family history or a history of dysplastic nevi are at significantly greater risk of developing multiple primary melanomas and should be enrolled in more intensive dermatologic surveillance programs. This high-risk subset of patients should also be further characterized genetically to further elucidate the biology and etiology of melanoma," the authors concluded.

In 2005, there will be an estimated 62,000 new cases of invasive melanoma and an estimated 7,600 deaths due to melanoma in the United States, according to background information in the article. Melanoma is the fifth leading cancer in men and the sixth leading cancer in women in the United States. The incidence of melanoma continues to rise at about 3 percent per year in the United States, with an estimated lifetime risk for an individual of 1.4 percent. The increasing incidence puts a larger portion of the population at risk not only for one primary melanoma but also for subsequent primary melanomas.