Comparing bowel and urinary domains of patient‐reported quality of life at the end of and 3 months post radiotherapy between intensity‐modulated radiotherapy and proton beam therapy for clinically localized prostate cancer

Purpose To prospectively assess acute differences in patient‐reported outcomes in bowel and urinary domains between intensity‐modulated radiotherapy (IMRT) and proton beam therapy (PBT) for prostate cancer. Methods and Materials Bowel function (BF), urinary irritative/obstructive symptoms (UO), and urinary incontinence (UI) domains of EPIC‐26 were collected in patients with T1‐T2 prostate cancer receiving IMRT or PBT at a tertiary cancer center (2015‐2018). Mean changes in domain scores were analyzed from pretreatment to the end of and 3 months post‐radiotherapy for each modality. A clinically meaningful change was defined as a score change >50% of the baseline standard deviation. Results A total of 157 patients receiving IMRT and 105 receiving PBT were included. There were no baseline differences in domain scores between cohorts. At the end of radiotherapy, there was significant and clinically meaningful worsening of BF and UO scores for patients receiving either modality. In the BF domain, the IMRT cohort experienced greater decrement (−13.0 vs −6.7, P