Toxicity analysis of postoperative image-guided intensity-modulated radiotherapy for prostate cancer.

Abstract

To report on the acute and late gastrointestinal (GI) and genitourinary (GU) toxicity associated with a unique technique of image-guided radiotherapy (IGRT) in patients undergoing postprostatectomy irradiation. Fifty patients were treated with intensity-modulated radiation therapy (IMRT) after radical prostatectomy. Daily image guidance was performed to localize the prostate bed using kilovoltage imaging or cone-beam computed tomography. The median prescription dose was 68 Gy (range, 62-68 Gy). Toxicity was graded every 3 to 6 months according to the Common Terminology Criteria for Adverse Events version 3.0. The median follow-up was 24 months (range, 13-38 months). Grade 2 acute GI and GU events occurred in 4 patients (8%) and 7 patients (14%), respectively. No Grade 3 or higher acute GI or GU toxicities were observed. Late Grade 2 GI and GU events occurred in 1 patient (2%) and 8 patients (16%), respectively. Only a single (2%) Grade 3 or higher late toxicity was observed. Image-guided IMRT in the postprostatectomy setting is associated with a low frequency of acute and late GI/GU toxicity. These results compare more favorably to radiotherapy techniques that do not use in-room image-guidance, suggesting that daily prostate bed localization may reduce the incidence of adverse events in patients undergoing postprostatectomy irradiation.