Clinical Outcomes And Late Toxicity Of Hypofractionated Intensity-Modulated Radiotherapy For High-Risk Prostate Cancer.

56Background: Since prostate cancer has intrinsic high radiation-fraction sensitivity, hypofractionated radiotherapy (HFRT) could offer treatment advantages. However, dose-escalated HFRT may increase risks of late genitourinary (GU) and gastrointestinal (GI) toxicity. Intensity-modulated radiotherapy (IMRT) can potentially deliver dose-escalated HFRT without increasing late toxicities. This study’s acute toxicity data was previously published. We now present five-year efficacy results and late toxicity data for prostate cancer patients treated with HFRT using IMRT. Methods: From 2005-2012, our Phase II prospective study enrolled one hundred patients with either high risk disease (one or more of: Stage ≥ T3, Gleason ≥ 8, or PSA ≥ 20 ng/mL) or high tier intermediate risk disease (Gleason 7 and PSA ≥ 15 ng/mL). All patients received HFRT using IMRT in 25 daily fractions. Sixty patients received 68 Gy to the prostate and proximal seminal vesicles, with simultaneous integrated boost (SIB) of 45 Gy to pelvic ly...