Epidemiologic studies have provided suggestive evidence of a link between cutaneous melanoma (CM) and breast cancer (BC). Moreover, carriers of mutations in the breast cancer predisposition gene, BRCA2, have an increased risk of melanoma while carriers of mutations in the melanoma susceptibility gene, CDKN2A, exhibit a higher than expected risk of breast cancer. These findings raise the possibility that pathways involved in the development of CM and BC overlap and that survivors of one cancer may be prone to develop the other. To this end, we set out to determine if survivors of female BC in the Surveillance, Epidemiology and End Result (SEER) database are at increased risk for CM and vice versa. We followed female BC patients registered in the 1973-1999 SEER database for development of a second CM and female CM patients for the development of a second BC. The expected number of cases was then compared to the observed number of cases using standardized incidence ratios. Overall, we found a modest but statistically significant increased risk of CM among female BC survivors and vice versa. Among young BC patients, we observed a 46% elevated risk of a second CM. Women who underwent radiation therapy exhibited a 42% increased risk for CM. The risks of BC among female CM survivors and CM among BC survivors were also elevated, albeit to a much lesser degree (overall, 11% and 16%, respectively). We found a mutual association between female BC and CM. The elevated risk for CM, especially among younger BC patients, suggests that the genetic observations from high-risk groups may also be operative at a much lower level in the general BC population.
Copyright 2004 Wiley-Liss, Inc.