Background: Patients with renal cell carcinoma (RCC) and malignant melanoma (MM) have an increased risk of additional malignancies. We identified characteristics of MM and RCC associated with a patient developing both cancers.
Methods: A total of 147,656 cases of RCC and 225,548 of MM submitted to the Surveillance, Epidemiology, and End Results database between 1973 and 2008 were analyzed. Standardized incidence ratios (SIR) with 95 % confidence intervals (CI) were calculated for MM after RCC and vice versa. Clinical and pathological characteristics were compared between patients with RCC or MM only and with both cancers using multivariable proportional hazards and competing risks regression models.
Results: Overall 1,241 patients developed both cancers. The crude incidence rates of RCC in patients with a prior MM diagnosis and vice versa were 5.2 and 9.4 per 10,000 person-years, respectively. There was an excess of MM in RCC patients (SIR 1.45, CI 1.34-1.57) and of RCC in MM patients (SIR 1.34, CI 1.25-1.43). Median years from RCC to MM diagnosis was 4.3 (2.0-7.8) and from MM to RCC 4.7(2.3-9.9). Patients with a history of MM had more papillary RCC (10.2 vs. 4.8 %, p = 0.01) and were more likely to be female (25.9 vs. 20.5 %, p < 0.001). On multivariable analyses, ocular MM was independently associated with subsequent RCC (HR 1.76 CI 1.24-2.49), as were increasing age, and male sex.
Conclusions: We confirmed a bidirectional association between RCC and MM. A history of MM was found to be associated with papillary RCC and advanced RCC. Ocular MM predicted an increased risk of RCC diagnosis. Further research is warranted into the mechanisms responsible for the association between RCC and MM.