Obesity and Outcomes in Patients with Metastatic Urothelial Carcinoma

Background: Obesity has been associated with worse outcomes in patients with clinically localized urothelial cancer. However, this impact has not been evaluated in metastatic disease. Objective: To assess the impact of obesity on outcomes of patients with metastatic urothelial cancer. Methods: Data from 537 patients were aggregated from eight phase II and phase III clinical trials investigating first-line cisplatin-based combination therapy in metastatic urothelial cancer. Chemotherapy regimen, adverse events, treatment response, and survival outcomes were compared across body mass index (BMI) and body surface area (BSA) categories. Results: BMI was classified according to WHO criteria (<18.5 underweight, 18.5-24.99 normal weight, 25-29.99 overweight, >30 obese). BSA was classified as either below or greater than or equal to (average for this cohort (1.87 m² for males and 1.66 m² for females). There was no significant difference in number of chemotherapy cycles, adverse events, and response rate or survival outcomes (overall and progression-free) across BMI and BSA categories. There was no significant difference in adverse events across BMI categories, but the incidences of embolic events and renal failure were higher in patients with an average or higher BSA than those with a lower than average BSA (6.6% vs. 3.1% for renal failure p = 0.06; 5.9% vs. 2.7% for renal failure, p = 0.07). There was no significant difference in response rate or survival outcomes (overall and progression-free) amongst BMI and BSA categories. Conclusions: Obese patients with metastatic urothelial cancer on cisplatin-based therapies have similar response rates, survival outcomes, and tolerability of cisplatin-based therapy to non-obese patients.