3161 - Differential Use of Radiotherapy Fractionation Regimens for Muscle-Invasive Bladder Cancer

M. Diven¹, J. A. Efstathiou², S. Delacroix³, and H. Nagar⁴; ¹New York Presbyterian Brooklyn Methodist Hospital, Brooklyn, NY, ²Department of Radiation Oncology, Harvard School of Medicine, Boston, MA, ³Louisiana State University, New Orleans, LA, ⁴Department of Radiation Oncology, NewYork-Presbyterian/Weill Cornell Medical Center, New York, NY

Purpose/Objective(s): The purpose of this study is to evaluate practice patterns for patients with clinically node negative T2 or T3 muscle invasive bladder cancer. Materials/

Methods: The NCDB Bladder cancer database was analyzed using statistical software in February-March 2024. Data from 773,366 cases from years 2004-2020 were available for analysis. The cohort was analyzed for pattern of initial therapy between either cystectomy or chemoradiation. Further analysis was performed by analyzing radiation therapy treatment information and stratifying patients based on dose/fractionation courses. Patients undergoing a course of EBRT with 55Gy in 20 fractions were considered as hypo-fractionated with remaining dose and fractionation combinations considered as not hypo-fractionated. Descriptive statistics were generated analyzing trends in local therapy, hypofractionation, concurrent chemotherapy (single agent vs. multi-agent or unspecified) and EBRT techniques (IMRT vs. not IMRT) over time.
Results: Of the 773,366 cases available in the dataset, 95,225 cases of clinical T2N0M0 or T3N0M0 transitional cell carcinoma of bladder primary were identified. 90.6% of cases were clinically T2 while 9.4% were clinically T3. Mean age at time of diagnosis was 73, [median age 74, 16-90]. 73.6% of patients were denoted Male and 26.4% Female. 90.4% were White race and 6.4% were Black race. In total, 47,441 (49.9%) of the patients did not receive definitive therapy while 40,422 (42.5%) underwent cystectomy and 7,226 (7.6%) underwent chemoRT. From 2013 to 2020 hypofractionation use increased from 1% to 15.2%. 141 of 270 (52.2%) patients treated with hypofractionation were treated at an Academic/Research program. Utilization of single agent concurrent chemotherapy increased from 46% to 61.1% in 2020. IMRT use increased from 7.5% in 2004 to 66.5% in 2020.
Conclusion: Definitive treatment for MIBC remains underutilized with 50% of patients receiving curative intent treatment in 2020. Adoption and utilization of hypofractionation for T2 or T3N0 MIBC is increasing over time with wider adoption.