Risk factors and survival outcomes of metachronous contralateral upper tract urothelial carcinoma.

Because population-based risk estimates for metachronous contralateral UTUC are lacking. In this study, we aimed to evaluate the risk and survival of metachronous contralateral upper tract urothelial carcinoma (UTUC) on a large population-based level. A total of 23,075 patients were identified from the Surveillance, Epidemiology, and End Results database (1973-2015), 144 (0.6%) patients developed metachronous contralateral UTUC (median of 32 months after diagnosis). The cumulative incidence at 10, 20, and 30 years of follow-up was 1.1%, 1.6%, and 2.6%, respectively. We applied Fine and Gray's competing risk regression model to determine the risk factors of a new contralateral, metachronous UTUC. The competing risk regression model demonstrated that older age (hazard ratio [HR] 0.75; 95% CI 0.67-0.85) and larger tumor size (HR 0.61; 95% CI 0.39-0.97) were associated with a significantly decreased risk of metachronous contralateral UTUC. However, bladder cancer presence was an independent risk factor for the development of contralateral tumors (HR 2.42; 95% CI 1.73-3.37). In addition, we demonstrated developing contralateral UTUC was not associated with poor prognosis by using Kaplan-Meier and multivariable analysis. Our findings suggest that metachronous contralateral UTUC is comparatively rare, and has not impact on survival. Importantly, patients with younger age, small tumours, and the presence of bladder cancer were more likely to develop a contralateral tumor, which may provide a rationale for lifelong surveillance in high-risk patients.