Presenter(s)
W. Majewski1, M. Bilski2,3, A. Kozub1, A. Misiorowska-Golosz1, and B. Staszewski4; 1Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice, Poland, 2Department of Radiotherapy, Medical University of Lublin, Lublin, Poland, 3Affidea Nu-med Center of Cancer Diagnostics and Therapy, Zamosc, Poland, 4St. John's Cancer Center, Lublin, Poland
Purpose/Objective(s):
Trimodality therapy (TMT) is considered an alternative to radical cystectomy; however, it remains underutilized and the optimal treatment schedule has not been established. The aim of this retrospective study was to analyze retrospectively outcomes of TMT with a simultaneous integrated boost (SIB) to the tumor/tumor bed in comparison to standard whole-bladder radiotherapy.Materials/Methods:
A total of 106 patients with muscle-invasive bladder cancer were treated with TMT between 2011 and 2025 in two centers in Poland. Group 1 included 86 patients treated with whole-bladder irradiation to a total dose of 64–66 Gy (81%), using 1.8–2.0 Gy per fraction. Group 2 consisted of 20 patients in whom a fiducial marker was placed in the tumor bed during initial TURBT; these patients received whole-bladder irradiation to 57 Gy in 30 fractions with SIB to the tumor/tumor bed to a total dose of 64.5 Gy. Whole-pelvis irradiation was delivered in 100% and 70% of patients in Groups 1 and 2, respectively. Concurrent cisplatin-based chemotherapy was administered in both groups. The planned schedules were usually 3 × 80 mg/m² or 5–6 × 35–40 mg/m² in Group 1 and 3 × 40 mg/m² in Group 2. Early and late genitourinary (GU) and gastrointestinal (GI) toxicity was assessed using the RTOG scale; hematologic toxicity was assessed with CTCAE scale. Long-term outcomes included local control (LC), overall survival (OS), and freedom from distant metastases (FFDM). Statistical analyses were performed using the ?² test (with Yates correction when appropriate) and the Kaplan–Meier method with log-rank test.Results: Baseline characteristics were similar between the groups: mean age 68 vs 70 years, T2 stage 59% vs 60%, hydronephrosis 18% vs 15%. The rate of high-grade tumors was significantly higher in Group 1 (73% vs 20%, p=0.0001). In the entire cohort, early G2+/G3+ GU toxicity occurred in 35%/8% of patients. By subgroup, this was 40%/10% in Group 1 and 15%/0% in Group 2. Early G2+ GI toxicity occurred in 28% of patients, with no G3+ events. Grade 3+ hematologic toxicity during radiotherapy occurred in 8% and 10% of patients, respectively. Of 91 evaluable patients for late toxicity, G2+/G3+ GU events occurred in 18%/5% overall (15%/3% in Group 1 and 25%/15% in Group 2). Late GI toxicity was rare (2% G2, no G3). A significant difference was observed only for early G2+ GU events (p=0.038). With a median follow-up of 67 months, 5-year LC, OS, and FFDM rates were 69%, 52%, and 64%, respectively. These outcomes were 63%, 51%, and 58% in Group 1 versus 84%, 62%, and 82% in Group 2. Differences were significant for OS and FFDM (p=0.048 and p=0.019).
Conclusion:
TMT achieved satisfactory outcomes, with results slightly favoring tumor/tumor bed boost over whole-bladder irradiation in well-selected patients, despite a lower cumulative cisplatin dose. Due to imbalance in tumor grade distribution, potential patient selection bias, and the retrospective design, these results should be interpreted with caution.