A pooled patient‐reported outcomes analysis of moderately hypofractionated proton beam therapy and photon‐based intensity modulated radiation therapy for low‐ or intermediate‐risk prostate cancer

Background We sought to characterize and compare late patient‐reported outcomes (PROs) after moderately hypofractionated intensity modulated radiation therapy (IMRT) and proton beam therapy (PBT) for localized prostate cancer (PC). Methods This multi‐institutional analysis included low‐ or intermediate‐risk group PC patients treated with moderately hypofractionated radiation to an intact prostate stratified by treatment modality: IMRT or PBT. The primary outcomes were prospectively collected patient‐reported late gastrointestinal (GI) and genitourinary (GU) toxicity assessed by International Prostate Symptom Score (IPSS) and Expanded PC Index Composite (EPIC). Multivariable regression analysis (MVA) controlling for age, race, and risk group tested the effect of time, treatment, and their interaction. Results 287 IMRT and 485 PBT patients were included. Intermediate risk group (81.2 vs. 68.2%; p