Impact of Obesity on Systemic Treatment Outcomes in Metastatic Urological Malignancies

Obesity increasingly influences treatment outcomes in urological malignancies (metastatic bladder cancer (BC), renal cell cancer (RCC), and prostate cancer (PC)). This study evaluated the impact of obesity on survival in patients with major metastatic urological cancers receiving systemic therapy.

Patients with metastatic BC, RCC, and PC treated at a high-volume center from 2017 to 2025 were retrospectively analyzed. In total, 387 patients were included (BC: n = 166; RCC: n = 63; PC: n = 158) and stratified by the body mass index [BMI]. Overall survival was assessed using restricted mean survival time (RMST) at predefined landmarks (24 months for BC and RCC; 36 months for PC).

Overall, 23.5% of the patients had obesity, with the highest prevalence in RCC (44.4%). In metastatic BC, obesity was not associated with differences in RMST at 24 months. In RCC, patients with obesity showed a numerical improvement in RMST and a significantly longer duration of systemic therapy. In contrast, patients with obesity with metastatic PC demonstrated significantly shorter RMST at 36 months than patients without obesity.

The prognostic impact of obesity differs across metastatic urological malignancies. While the present findings support an obesity paradox in RCC, obesity was associated with worse survival in metastatic PC but showed no impact on survival in BC. These results highlight the need for tumor-specific biological interpretation of BMI-related outcomes.