Trends and Predictors of Hypofractionated and Intensity-Modulated Radiotherapy for Organ Preservation in Bladder Cancer.

Use of hypofractionated radiation (HFRT) and intensity-modulated radiation (IMRT) for organ preservation in bladder cancer is controversial and highly variable. We investigated practice patterns, trends, and predictors of HFRT and IMRT.

The National Cancer Database was queried for patients with muscle-invasive, non-metastatic urothelial bladder cancer, treated with definitive (chemo)radiotherapy between 2004 and 2017. HFRT was defined as 50 to 60 Gy at >2 Gy/fraction. Multivariable logistic regression was used to identify predictors of receiving HFRT or IMRT. Multivariable Cox regression was used to model overall survival (OS), adjusting for potential confounders such as age, comorbidity, and chemotherapy.

Of 5132 patients identified, 490 (9.5%) received HFRT, and only 334 (6.5%) received ≥2.5 Gy/fraction. HFRT patients were significantly older, less fit, and less likely to receive chemotherapy relative to CFRT, even after controlling for age and comorbidity (adjusted odds ratio 0.36, 95% confidence interval [CI] 0.29-0.45, P < .0001). Utilization of HFRT and IMRT increased over time (P < .0001), reaching 22.5% and 47.7%, respectively, by 2017. Among patients treated with CFRT, OS was similar with or without IMRT (P = .46). Among patients treated with HFRT, IMRT was associated with increased survival (3-year OS 35% vs. 24%, P = .03), which persisted in multivariable analysis (adjusted hazard ratio 0.71, 95% CI 0.52-0.98, P = .04).

HFRT is largely underutilized, being primarily reserved for older, frailer patients. Chemotherapy is significantly underused with HFRT relative to CFRT. IMRT is used frequently and was associated with equivalent or modestly increased overall survival.

Clinical genitourinary cancer. 2021 Nov 11 [Epub ahead of print]

Michael Xiang, Albert J Chang, Karim Chamie, Alexandra Drakaki, Erqi L Pollom, Michael L Steinberg, Amar U Kishan

Department of Radiation Oncology, University of California Los Angeles, Los Angeles, CA. Electronic address: ., Department of Radiation Oncology, University of California Los Angeles, Los Angeles, CA., Department of Urology, University of California Los Angeles, Los Angeles, CA., Department of Urologic Oncology, University of California Los Angeles, Los Angeles, CA., Department of Radiation Oncology, Stanford University, Stanford, CA.

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