ESTRO 2025 - Abstract Book

S1894

Clinical - Urology

ESTRO 2025

Marseille, France. 8 Radiation oncology, Centre Georges-Francois Leclerc, Dijon, France. 9 Radiation oncology, Hopital européen Georges Pompidou, Paris, France. 10 Radiation oncology, Centre Francois Baclesse, Caen, France

Purpose/Objective: Trimodal therapy (TMT) is now considered a viable treatment option for muscle-invasive bladder cancer (MIBC) in selected patients. The optimal chemotherapy regimen remains unknown, as various drugs can be proposed. We present the results of a phase II trial evaluating the combination of cisplatin (CDDP) with twice-weekly gemcitabine (GEM) and radiation therapy (RT) after its evaluation in phase I (1,2). Material/Methods: Patients with pT2-pT3N0M0 MIBC, following macroscopically complete transurethral bladder tumor resection (TURBT), were enrolled in this study. Post-TURBT, patients received concomitant radiation therapy (1.8 Gy/fraction, 63 Gy to the bladder, 45 Gy to the pelvis) and chemotherapy (CDDP 20 mg/m²/day over 4 days every 21 days and gemcitabine 25 mg/m² twice a week). The primary endpoint was 2-year disease-free survival (DFS). Secondary endpoints included overall survival (OS) and toxicities. A 1:2 randomization was planned to include 36 patients in the control arm and 73 patients in the experimental arm. Results: Sixty-nine patients were included: 24 in the RT/CDDP arm and 45 in the RT/CDDP/GEM arm. The median follow-up was 63 months. The 2-year DFS rate did not differ significantly between the RT/CDDP arm and the RT/CDDP/GEM arm (58.3% vs. 60.0%, p = 0.216). The median DFS was 29.8 months in the RT/CDDP arm compared to 37.4 months in the RT/CDDP/GEM arm. The 24- and 60-month OS rates were 91.3% and 66.8% in the RT/CDDP arm, versus 66.7% and 53.7% in the RT/CDDP/GEM arm. Using the log-rank test, there was no significant difference between the two groups for OS (p = 0.145) and DFS (p = 0.891). Except for cytopenias, there was no difference in terms of toxicities between the two groups.