Phase I study of moderately hypo-fractionated intensity modulated radiotherapy after prostatectomy

Objective To assess the acute toxicity of a hypo-fractionated regimen of intensity-modulated radiotherapy to the prostatic bed after prostatectomy. Methods From February to August 2017, twenty cases with prostate adenocarcinoma after prostatectomy were recruited. The prescribed dose to the whole pelvis and the prostatic bed was 45 Gy delivered in 1.8 Gy per fraction and 62.75 Gy delivered in 2.51 Gy per fraction, respectively. Acute toxicity was recorded and graded according to Radiation Therapy Oncology Group (RTOG) criteria and Common Terminology Criteria for Adverse Events (CTCAE) 4.0. Results The median follow-up was 7.5 months. Grade 2 acute genitourinary and gastrointestinal toxicity was observed respectively in two cases (10%) and one (5%), respectively. Two cases(10%) complained of grade 2 urinary incontinence during radiation therapy, but recovered to grade 0 or grade 1 after the first month of follow-up. Conclusions After prostatectomy, moderately hypo-fractionated radiotherapy (2.51 Gy×25) compared with conventional fractionated radiotherapy previously reported did not increase the risk of acute toxicity. The incidence of urinary incontinence did not increase during short-term of follow-up. Key words: Prostatectom cancer; Moderately hypo-fractionated radiotherapy; Postoperative radiotherapy