Long-Term Patient-Reported Bowel and Urinary Quality of Life in Patients Treated with Intensity-Modulated Radiotherapy and Intensity-Modulated Proton Therapy for Localized Prostate Cancer

Abstract

To assess long-term differences in patient-reported outcomes in bowel and urinary domains between intensity-modulated radiotherapy (IMRT) and intensity-modulated proton therapy (IMPT) for prostate cancer. 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 IMPT at a tertiary cancer center (2015-2018). Mean changes in domain scores were analyzed from pretreatment to 24 months post-radiotherapy for each modality. A clinically meaningful change was defined as a score change >50% of the standard deviation of a baseline score. A total of 82 patients treated with IMRT (52.2%) and 56 patients treated with IMPT (53.3%) completed the questionnaire at baseline and 24 months post-RT. There were no baseline differences in domain scores between treatment modalities. At 24 months post-radiotherapy, there was significant and clinically meaningful decline of BF mean score in the IMRT cohort (-4.52 [range -50, 29.17], p = 0.003), whereas the decline in BF score did not reach statistical significance (-1.88 [range -37.5,50], p = 0.046) when accounting for the Bonferroni adjustment nor clinical relevance in the IMPT cohort. A higher proportion of patients treated with IMRT had a clinically relevant reduction in BF when compared with IMPT (47.37% vs 25.93%, p = 0.017). The mean changes in UI and UO scores of the IMRT and IMPT cohorts were neither statically significant nor clinically relevant. IMPT has less decrement in BF than IMRT at 24 months post-RT, while there was no differential effect on UO and UI.