Risk factors for metachronous bilateral renal cell carcinoma: A surveillance, epidemiology, and end results analysis.

Our findings suggest that the cumulative incidence of metachronous, contralateral RCC may be higher than previously reported. Younger age, black race, papillary histology, and male sex increase the risk of metachronous, contralateral RCC development. The high SIRs seen in all demographic groups may support a rationale for lifelong surveillance, especially in high-risk subgroups with early disease onset.