Patient Reported Quality of Life after Moderately Hypofractionated Proton Beam Therapy or Intensity Modulated Radiation Therapy for Prostate Cancer

Abstract

<h3>Purpose/Objective(s)</h3> We aim to quantify and compare changes in patient reported quality of life (PRQOL) after moderately hypofractionated (MHF) Proton Beam Therapy (PBT) or Intensity Modulated Radiation Therapy (IMRT) for prostate cancer (PC). <h3>Materials/Methods</h3> This multi-institutional analysis included patients with NCCN low or intermediate risk PC treated at 4 tertiary cancer centers with MHF PBT or IMRT with prospective PRQOL collection. Patients completed International Prostate Symptom Score (IPSS) and Expanded Prostate Cancer Index Composite for Clinical Practice (EPIC) pre-treatment and at 3-to-6-month intervals starting at the end of treatment. EPIC is a questionnaire measuring health related quality of life (HRQOL) domains of genitourinary (GU), gastrointestinal (GI), sexual, and hormonal function. Questions are scored from 0 (no problem) to 4 (big problem). EPIC score of 3 or more was considered a meaningful QOL decrement. IPSS measures GU HRQOL; each question is measured from a score of 0 to 5 with a maximum score of 35. Baseline characteristics were compared with Chi squared and t test for IPSS. Models were limited to long term data, at 12 and 36 months. Generalized linear regression models testing effects of time, treatment, and their interaction were fit via Generalized Estimating Equations, controlling for age, race, and NCCN risk group. <h3>Results</h3> 287 IMRT and 485 PBT patients were included. Intermediate NCCN risk group (81.2 vs. 68.2%; p < 0.001), median age at diagnosis (70 vs 66.9 years; p < 0.001) were higher in the IMRT group. Mean IPSS was slightly worse at baseline in the PBT arm (+0.22; CI, -1.54 – 1.10; p=0.74) and slightly better at 3 years (-0.09; CI, -1.48 – 1.65; p=0.91). On Poisson regression controlling for age, race, and NCCN risk group, PBT IPSS trended worse at 12 months (OR, 1.19; CI, 0.98 - 1.44; p=0.077) without any difference at 36 months (OR, 1.08; CI, 0.80 - 1.26; p=0.94). Similarly, EPIC questionnaire for overall GI function trended worse with PBT at 12 months (CI, 0.83 - 16.27; p=0.085) without difference at 36 months (CI, 0.49 - 12.27, p=0.27). 4.9% and 4.8% patients in the PBT and IMRT arms, respectively, rated their overall GI function at 12 months as a severe problem. Among PBT and IMRT patients combined, severe GU concerns were unlikely at 12 months (GU frequency: 17.5; GU pain: 3.6; stream problem: 11.2%). <h3>Conclusion</h3> PRQOL showed a non-significant trend toward worse 1-year overall GI function and IPSS for PBT; this effect was not present at 3 years. In this multi-institutional, prospective study of PC, long-term GU and GI function was not significantly different between PBT or IMRT arms.