Postoperative intensity-modulated radiotherapy with simultaneous integrated boost in prostate cancer: A dose-escalation trial

ObjectivesTo determine the recommended phase II dose of postoperative accelerated intensity modulated radiotherapy (IMRT) for prostate cancer.Material and methodsStep and shoot IMRT with simultaneous integrated boost (SIB) was delivered in 25 fractions over 5 weeks to patients with high risk resected prostate adenocarcinoma (stage pT3-4 and/or positive surgical margins). Pelvic nodes received 45 Gy at 1.8 Gy/fraction; dose escalation was performed only to the prostate bed (planned dose escalation: 56.8 Gy at 2.27 Gy/fraction, 59.7 Gy at 2.39 Gy/fraction, 61.25 Gy at 2.45 Gy/fraction, 62.5 Gy at 2.5 Gy/fraction). Dose-limiting toxicity (DLT) was any grade ≥ 3 acute toxicity (RTOG score).ResultsTwenty-five patients were treated: 7 patients at the 56.75 Gy dose level, 6 patients at each subsequent dose level. Pathologic stages were: pT2c: 2; pT3a: 11; pT3b: 12; pN0: 22; pN1: 3; R0: 7; R1: 18. Median follow-up time was 19 months (range: 6–36 months). No patient experienced DLT. Grade 1–2 acute rectal and urologic toxicity was common (17 and 22 patients, respectively).ConclusionsThe recommended dose was 62.5 Gy in 2.5 Gy/fraction. Postoperative hypofractionated IMRT SIB for prostate cancer seemed to be well tolerated and could be tested in phase II studies.