Genetic Melanoma Risk Less Than Previously Thought

NEW YORK (Reuters Health) - The findings from a new study indicate that carriers of the CDKN2A mutation have a 28-percent lifetime risk of melanoma, much lower than the 58 percent to 91 percent risk previously identified in studies of multiple-case families.

"In studies of multiple-case families, these families could well be linked by other genes that contribute to the risk of melanoma as well as the one you're looking at," lead author Dr. Colin B. Begg, from Memorial Sloan-Kettering Cancer Center in New York, told Reuters Health. "When you separate out the family history like we did in our study, you tend to see a more representative estimate of the risk."

The study, which is reported in the Journal of the National Cancer Institute, involved an analysis of cases of melanoma, the most serious type of skin cancer, in nine geographic regions in Australia, Canada, the United States and Italy.

DNA from 3,550 melanoma patients was analyzed for CDKN2A mutations. The melanoma histories of the close relatives of these patients were used to determine the lifetime risk of melanoma associated with CDKN2A mutation carrier status.

Overall, 65 CDKN2A mutation carriers were identified. The risk of developing melanoma among mutation carriers ranged from 14 percent by age 50 years to 28 percent by age 80 years.

While 18 of the melanoma patients had at least three relatives with melanoma, only one was a CDNK2A mutation carrier, according to the report.

"This indicates that CDNK2A mutations are rare," Begg noted. "So, genetic testing for the mutation is going to reveal relatively few carriers."

Begg said his team is further analyzing the data from this study to identify other potential genetic risk factors for melanoma.

SOURCE: Journal of the National Cancer Institute, October 19, 2005.