Uveal melanoma: a study on incidence of additional cancers in the Swedish population.

PURPOSE To investigate the occurrence of other primary malignancies before and after diagnosis of uveal melanoma in a Swedish population. METHODS In the Swedish Cancer Registry 2995 patients with uveal melanoma were notified during the period 1960 to 1998. In the same registry, a search for additional malignancies among these patients was performed. A matched case-control study with 2,916 patients and 14,577 population control subjects was set up for malignancies before diagnosis of uveal melanoma. Malignancies after diagnosis of uveal melanoma were evaluated in 2,995 patients through standardized incidence ratios (SIRs), based on the expected rates in the Swedish population. RESULTS Before the diagnosis of uveal melanoma, the odds ratio (OR) for the risk of cancer was 1.25 (95% CI: 0.98-1.59). No significantly increased risk was found for any specific malignancy. The OR for cutaneous melanoma was 1.74 (95% CI: 0.78-3.89). The risk of subsequent cancers was increased, SIR 1.13 (95% CI: 1.02-1.26). After reevaluation of archival specimens, the SIR of a cutaneous melanoma's developing after a uveal melanoma was found to be 1.75 (95% CI: 0.87-3.12). CONCLUSIONS An increased risk of second primary cancers was observed among Swedish patients with uveal melanoma. Metastases from uveal melanoma were found to be misclassified as cutaneous melanoma or as primary liver cancer.