"These patients should undergo intensive dermatologic screening and should consider genetic testing," write Cristina Ferrone, MD, and colleagues.
Ferrone's team works at New York's Memorial Sloan-Kettering Cancer Center. Their study appears in The Journal of the American Medical Association.
About Multiple Melanoma Skin Cancer Skin Cancer Findings
Melanoma is a type of skin cancer. Here are some U.S. melanoma facts from Ferrone's report:
Skin Cancer Findings
Ferrone's team studied more than 4,400 patients from Memorial Sloan-Kettering Cancer Center who had their first melanoma diagnosed between 1996 and 2002. The patients were about 55 years old when they learned they had melanoma skin cancer.
Some patients -- 385 people, or about 9% of the group -- had more than one melanoma (multiple melanomas). They were more likely to have a family history of melanoma or personal history of dysplastic nevi, or both. Dysplastic nevi are abnormal moles that may become precancerous. The researchers note that they may be present in 5% to 10% of the general population.
Among people with multiple melanomas, 21% had had a family relative with melanoma. Only 12% of those with single melanoma had a family history of melanoma. For those with multiple melanomas, 39% had a prior history of dysplastic nevi vs. 18% of the people with single melanoma.
Family History Raises Risk
About 11% of patients with just one melanoma added a second melanoma within five years.
People with one melanoma and a family history of melanoma were at higher risk for additional melanomas. About 20% of them added more melanomas within five years, the study shows.
Dermatologists can screen for skin cancer. Skin protection with the use of sun block and appropriate clothing coverage is also important. Genetic testing of high-risk patients could help scientists learn more about melanomas, write the researchers.