Comparative outcomes of chemoradiotherapy regimens in muscle-invasive bladder cancer: A retrospective cohort study.

Abstract

738 Background: Bladder-preserving chemoradiotherapy (CRT) is an organ-sparing alternative to radical cystectomy for muscle-invasive bladder cancer (MIBC). This study compared outcomes and toxicity among three CRT regimens: weekly cisplatin, 5-fluorouracil plus mitomycin C (5-FU + MMC), and weekly low-dose gemcitabine. Methods: Patients with cT2–T4a N0-N1–N1 MIBC who underwent maximal TURBT followed by definitive CRT (median 64 Gy) were retrospectively analyzed. Primary endpoints were overall survival (OS) and disease-free survival (DFS). Analyses used Kaplan–Meier, Cox regression, and inverse probability of treatment weighting (IPTW). Results: Ninety-eight patients were included (median age 73; 79% male). Complete response occurred in 84% overall: 75% cisplatin, 84% 5-FU+MMC, 91% gemcitabine (p = 0.39). After 37 months’ follow-up, 5-year OS was 52% (p = 0.63), 3-year DFS 46% (p = 0.40). Distant relapse 50%; bladder-only 3%. Grade ≥3 toxicity 20% overall—22% cisplatin, 23% 5-FU+MMC, 13% gemcitabine (p = 0.58). Nodal disease predicted worse OS (HR 2.5, 95% CI 1.0–6.2; p = 0.04); regimen was not prognostic. IPTW confirmed results. Conclusions: Trimodality CRT achieved durable bladder preservation (~50% 5-year OS) with low local relapse. Efficacy was similar across regimens; gemcitabine showed lower toxicity. Distant relapse predominated, underscoring need for improved systemic therapy. Baseline characteristics, treatment response, survival, and toxicity by chemotherapy regimen. Parameter Cisplatin (n=32) 5-FU+MMC (n=34) Gemcitabine (n=32) p-value N1 disease (%) 28 15 10 0.01 Neoadjuvant chemotherapy (%) 28 12 15 0.10 Complete response (%) 81 85 88 0.38 3-year OS (%) 63 65 72 0.63 5-year OS (%) 50 52 55 0.62 3-year DFS (%) 44 47 48 0.40 Grade ≥3 toxicity (%) 22 21 12.5 0.25 Isolated bladder relapse (%) 3 3 3 0.95 Distant failures (%) 53 48 50 0.80 Comparative outcomes among patients treated with concurrent chemoradiotherapy (CTRT) using cisplatin-, 5-fluorouracil plus mitomycin-C (5-FU+MMC)-, or gemcitabine-based regimens. Percentages denote the proportion of patients per group. Complete response (CR) was defined radiologically and/or cystoscopically after CTRT. OS and DFS were measured from treatment start to death or recurrence. Grade ≥3 toxicity reflects clinically significant events retrospectively classified per CTCAE v5.0 where applicable. p-values were from chi-square or Fisher’s exact test; <0.05 was significant.