For a study, researchers sought to report acute changes in patient-reported quality of life (PRQOL) using the EPIC-26 questionnaire, a 26-item expanded prostate index composite, using hypofractionated intensity-modulated proton beam therapy (H-IMPT) targeting the prostate and the pelvic lymph nodes for high-risk or unfavorable intermediate-risk prostate cancer.

The study enrolled 55 patients. In 25 fractions, H-IMPT delivered 67.5 GyE to the prostate and seminal vesicles and 45 GyE to the pelvic lymph nodes. The urinary incontinence (UI), urinary irritative/obstructive symptoms (UO), and bowel function (BF) areas of the EPIC-26 questionnaire were used to measure PRQOL. The mean changes in domain scores from baseline through the conclusion of therapy and three months after treatment were examined. A score change of >50% of the baseline standard deviation was deemed to be a clinically significant change (or minimum critical change).

UO, UI, and BF had baseline mean scores of 84.6, 91.1, and 95.3, respectively. In contrast to the drop in UI score, which was statistically significant but not clinically meaningful (-13.7), the decline in UO and BF ratings at the therapy conclusion was clinically and statistically meaningful (-13.5 and -2.3, respectively). UO, UI, and BF scores decreased clinically significant amounts in 53.5%, 22.7%, and 73.2% of the patients, respectively. All 3 mean scores improved 3 months after therapy, and there were fewer patients who saw a clinically significant drop in their UO, UI, or BF scores (18.4%, 20.5%, and 45.0%, respectively). The mean UO and UI scores did not significantly change from baseline, but the mean BF score stayed lower and the difference was clinically significant.

At the conclusion of the H-IMPT, the PRQOL UO, UI, and BF ratings decreased. Three months after therapy, UO and UI scores indicated improvement and were comparable to the pretreatment levels. However, the BF score continued to fall with a clinically significant decline 3 months after therapy.