ESTRO 2025 - Abstract Book

S1980

Clinical - Urology

ESTRO 2025

1921

Poster Discussion Adjuvant radiotherapy in patients with pathological high-risk bladder cancer: Acute toxicity from a randomised phase II study (GETUG-AFU 30) Paul Sargos 1 , Géraldine Pignot 2 , Carine Bellera 3 , Pascal Pommier 4 , Etienne Martin 5 , Pierre Clavere 6 , Christophe Hennequin 7 , Jean-Luc Hoepffner 8 , David Pasquier 9 , Mathieu Roumiguié 10 , Sébastien Crouzet 11 , Luc Cormier 12 , Vanessa Schartner 13 , Noémie Huchet 3 , Gautier Marcq 14 , Jonathan Khalifa 15 1 Radiotherapy, Institut Bergonié, Bordeaux, France. 2 Oncological Surgery, Institut Paoli-Calmettes, Marseille, France. 3 Clinical and Epidemiological Research Unit, Institut Bergonié, Bordeaux, France. 4 Radiotherapy, Centre Léon Bérard, Lyon, France. 5 Radiotherapy, Georges-François Leclerc Center, Dijon, France. 6 Radiotherapy, CHU de Limoges, Limoges, France. 7 Radiotherapy, Hopital Saint-Louis, Paris, France. 8 Urology, Clinique Saint-Augustin, Bordeaux, France. 9 Radiotherapy, Centre Oscar Lambret, Lille, France. 10 Urology, CHU de Rangueuil, Toulouse, France. 11 Urology, Hospices Civils, Lyon, France. 12 Urology, CHU François Mitterand, Dijon, France. 13 Research and Development, Unicancer, Paris, France. 14 Urology, CHU de Lille, Lille, France. 15 Radiotherapy, Institut Universitaire du Cancer, Toulouse, France Purpose/Objective: Pathological high-risk muscle-invasive bladder cancer (MIBC) has a poor prognosis. Historically, adjuvant radiotherapy (RT) decreases the incidence of local and distant recurrences but induces a significant rate of toxicity. We aim to report acute toxicity from a multicentric phase II randomized trial evaluating adjuvant intensity modulated radiotherapy (IMRT) after radical cystectomy (RC) and pelvic lymph-nodes dissection with or without peri-operative chemotherapy. Material/Methods: Pathological high-risk MIBC was defined as pT3a-4b and/or pN1-2 and/or patients with positive surgical margins (R1). Patients with R1 resection and with orthotopic neo-bladder reconstruction as urinary diversion were not eligible. Patients were randomized (3:1) between adjuvant RT (arm A) and observation (arm B). Patients received 50.4 Gy in 28 fractions with IMRT given to the pelvic lymph nodes ± cystectomy bed (in case of positive margins). The primary outcome aimed to assess efficacy of adjuvant RT in terms of pelvic recurrence-free survival at 3 years. Here, we report on acute toxicity (<6 months after treatment) evaluated using the NCI CTCAE Version N°4.0. Results: A total of 80 patients were included (arm A=58, arm B=22); 74 of them were eligible for toxicity analysis. Median age was 66 yo. Positive lymph-nodes were found in 54% of the patients and 15% were R1. The median delay between RC and RT was 3.2 months (+/-6.4 months). Moreover, 59.5% patients received neoadjuvant chemotherapy. In the RT arm, only 1 patient has experienced treatment discontinuation due to toxicity (3 days, due to grade 3 anemia). All patients completed RT. In the RT arm, 14 patients (26.9%) developed acute grade 2 gastrointestinal (GI) toxicity (essentially diarrhea, constipation and flatulence); in arm B, 1 patient (4.5%) developed acute grade 2 GI toxicity. In the RT arm, 1 patient (1.9%) developed acute grade 3 GI toxicity (bowel obstruction) and 1 patient developed acute grade 4 GI toxicity (impaction of intestine); in arm B, no grade 3 or 4 GI toxicity were observed. Conclusion: From a randomized multicentric phase II trial, acute toxicity analysis confirm the safety of adjuvant IMRT for pathological high-risk MIBC with low rates of GI toxicity. Efficacy end-points results are awaited.

Keywords: Adjuvant radiotherapy, Bladder cancer, Toxicity