Risk of Second Primary Cancer in Survivors of In Situ Melanoma.

Survivors of invasive melanoma have an increased risk of developing second primary cancers; however, similar risks associated with in situ melanoma have not been established. We evaluated 39,872 survivors of first primary in situ melanoma diagnosed from 1982 through 2012 in Queensland, Australia. Relative risk of second nonmelanoma primary cancers was estimated from standardized incidence ratios with 95% confidence intervals. A total of 4,823 (12%) in situ melanoma survivors developed a second primary cancer. A small increased risk (6%) compared with the general population was found. In those younger than 50 years, risk was increased by 14% for all cancers combined. In situ melanoma survivors had significantly increased risks of developing lip, thyroid, pancreatic, and brain cancers and decreased risks of head and neck, and lung cancers. Male in situ melanoma survivors had a significantly increased risk of prostate cancer; female survivors had an increased risk of thyroid cancer and lymphoid leukemia. Findings indicate that in situ melanoma may predict the diagnosis of certain second primary cancers. This altered risk may be due to biological, behavioral, or genetic factors or increased medical surveillance, and it requires further investigation, particularly among people younger than 50 years.