Patient reported outcomes in NRG Oncology/RTOG 0938, evaluating two ultrahypofractionated regimens (UHR) for prostate cancer (CaP).

27 Background: The considerable interest in short UHR 5-12 fractions(fr) in management of CaP is based on potential radiobiological advantages, patient convenience & resource allocation benefits. Prior to comparison with standard RT regimens (SRTR), a study was undertaken whose primary objective was to demonstrate that 1-year health-related quality of life (HRQOL) for at least one UHR arm was not significantly lower than baseline as measured by the Bowel & Urinary domains EPIC instrument(EPIC B&U). Secondary objectives included acute & late GI & GU toxicity. Methods: RTOG 0938 is a randomized phase II study of CaP patients(pts), (Gleason score 2-6, stage T1-2a & PSA < 10 ng/mL) receiving 36.25 Gy (5 fr of 7.25 Gy in 2 wks), or 51.6 Gy (12 fr of 4.3 Gy in 2.5 wks). Pts were stratified according to RT technique – Cyberknife vs IMRT/VMAT or protons. A change in EPIC bowel domain score (baseline to 1-year) > 5 points & in EPIC urinary domain score > 2 points were felt to be clinically significant. The frequency for > 5 point change in bowel score (FREQE-B) in ≤ 35% of pts was considered acceptable, with the frequency ≥ 55% unacceptable. Similarly, the frequency for > 2 point change in urinary score (FREQE-U) in ≤ 40% was considered acceptable, with the frequency ≥ 60% unacceptable. A sample size of 156 pts was needed for 95% power with one-sided significance level of 0.025 to preserve an overall level of 0.05. Results: 240 pts were enrolled to ensure adequacy of data for analysis. The compliance for HRQOL completion was good ( > 80%). The 1 year FREQE-B for 5 fr was 23.5% (p < 0.001) & 12 fr was 23.1% (p < 0.001). The 1 year FREQE-U for 5 fr was 35.3% (p < 0.001) & 12 fr was 34.7% (p < 0.001). Conclusions: This study confirms that based on changes in EPIC B&U (baseline to 1-year), acute & late toxicity, both the 5 & 12 fr regimens are well tolerated. These UHR need to be compared to current SRTR in the context of a RCT with efficacy & toxicity endpoints. Supported by grants U10CA21661, U10CA180868, U10CA180822, U10CA37422, UG1CA189867 from the National Cancer Institute (NCI). Clinical trial information: NCT01434290. [Table: see text]