Primary Endpoint Analysis of a Randomized Phase III Trial of Hypofractionated vs. Conventional Post-Prostatectomy Radiotherapy: NRG Oncology GU003.

Purpose/Objective(s) To determine if hypofractionated post-operative prostate bed radiotherapy (HYPORT) does not increase patient-reported genitourinary (GU) or gastrointestinal (GI) toxicity over conventionally fractionated post-operative radiotherapy (COPORT). Materials/Methods Eligibility criteria were: 1) an undetectable PSA ( Results Between July 2017 and July 2018, 298 patients were screened and 296 were randomized: 144 to HYPORT and 152 to COPORT. Compliance with the EPIC was 100% at baseline, 83% at the end of RT, 77% at 6 months, 78% at 12 months, and 73% at 24 months. At the end of RT, the HYPORT and COPORT mean GU change scores were neither clinically significant nor significantly different and remained so at 6 and 12 months. The mean GI change scores for HYPORT and COPORT were both clinically significant and significantly different at the end of RT (HYPORT mean GI = -15.0 vs COPORT mean GI = -6.8 P ≤ 0.01). However, both the HYPORT and COPORT mean GI change scores clinically and statistically significant differences were resolved at 6 and 12 months. The 24-month mean GU and GI change scores for HYPORT and COPORT remained neither clinically nor statistically significant (HYPORT mean GU = -5.2 vs COPORT mean GU = -3.0, P = 0.81; HYPORT mean GI = -2.2 vs COPORT mean GI = -1.5, P = 0.12). With a median follow-up for censored patients of 2.1 years, there was no difference between HYPORT versus COPORT for biochemical failure defined as a PSA ≥ 0.4 ng/mL followed by a value higher than the first by any amount (2-yr actuarial, 12% vs 8%, P = 0.29) or local failure (2-yr actuarial, 0.7% vs 0.8%, P = 0.35). Conclusion HYPORT is non-inferior to COPORT in terms of late patient-reported GU or GI toxicity. More follow-up is needed to appropriately assess disease control endpoints. In some clinic scenarios, HYPORT may be considered an acceptable practice standard.