Phase I Dose Escalation Trial Of Stereotactic Radiotherapy Prior To Robotic Prostatectomy In High Risk Prostate Cancer

Background: The aim of the study was to investigate the safety of combining preoperative stereotactic body radiotherapy (SBRT) with robotic radical prostatectomy (RP) for high risk prostate cancer (HRCaP). Many patients with HRCaP will require adjuvant or salvage radiotherapy after RP. The addition of preoperative SBRT before RP may spare patients from subsequent prolonged courses of RT.Materials and methods: Eligible patients had NCCN HRCaP and received a total of 25 Gy or 30 Gy in five daily fractions of SBRT to the prostate and seminal vesicles followed by robotic RP with pelvic lymphadenectomy 31-45 days later. The primary endpoint was prevalence of acute genitourinary (GU) and gastrointestinal (GI) toxicity. Secondary endpoints were patient-reported quality of life (QOL) and biochemical recurrence (BcR).Results: Three patients received preoperative SBRT to 25 Gy and four received 30 Gy. Median follow-up was 18 months. Highest toxicity was grade 2 and 3 in six (85.7%) and one (14.3%) patients, respectively. All patients developed grade 2 erectile dysfunction and 4 of 7 (57%) developed grade 2 urinary incontinence (UI) within a month after surgery. One patient developed acute grade 3 UI, but there was no grade 4 toxicity. One patient experienced acute grade 2 hemorrhoidal bleeding. On QOL, acute GU complaints were common and peaked within 3 months. Bowel symptoms were mild. Two patients with pN+ experienced BcR.Conclusions: Preoperative SBRT before robotic RP in HRCaP is feasible and safe. The severity of acute GU toxicity with preoperative SBRT may be worse than RP alone, while bowel toxicity was mild.