Patient-Reported Quality of Life Outcomes after Moderately Hypofractionated and Normofractionated Proton Therapy for Localized Prostate Cancer

SIMPLE SUMMARY: For patients with localized prostate cancer (PCa), information on the quality of life (QOL) after treatment is important when determining their preferred treatment option. In external beam radiation therapy, moderate hypofractionation (MH) is becoming an alternative standard for PCa treatment and MH is increasingly used in proton therapy (PT). Although MHPT is a promising strategy, there is little evidence regarding the data of long-term QOL after MHPT. This study evaluated patient-reported QOL over three years after MHPT and compared the data with that after normofractionated PT (NFPT) using the Expanded Prostate Cancer Index Composite-50. We revealed urinary QOL was temporarily decreased with clinically meaningful changes at 1 month, but did not observe clinically meaningful QOL deterioration in other assessment points in the urinary, bowel, and sexual domains over three years after MHPT. In addition, the QOL after MHPT and NFPT was similar overall. ABSTRACT: We retrospectively evaluated the three-year patient-reported quality of life (QOL) after moderately hypofractionated proton therapy (MHPT) for localized prostate cancer in comparison with that after normofractionated PT (NFPT) using the Expanded Prostate Cancer Index Composite-50. Patients who received MHPT (60–63 Gy (relative biological effectiveness equivalents; RBE)/20–21 fractions) (n = 343) or NFPT (74–78 Gy (RBE)/37–39 fractions) (n = 296) between 2013 and 2016 were analyzed. The minimum clinically important difference (MCID) threshold was defined as one-half of a standard deviation of the baseline value. The median follow-up was 56 months and 83% completed questionnaires at 36 months. Clinically meaningful score deterioration was observed in the urinary domain at 1 month in both groups and in the sexual domain at 6–36 months in the NFPT group, but not observed in the bowel domain. At 36 months, the mean score change for urinary summary was −0.3 (MHPT) and −1.6 points (NFPT), and that for bowel summary was +0.1 and −2.0 points; the proportion of patients with MCID was 21% and 24% for urinary summary and 18% and 29% for bowel summary. Overall, MHPT had small negative impacts on QOL over three years, and the QOL after MHPT and NFPT was similar.