Radiotherapy is a treatment option for prostate cancer patients after rectal surgery; however, the toxicity profile of radiotherapy for such patients has not been elucidated. This study aimed to evaluate the long-term toxicities and efficacy of intensity-modulated radiotherapy (IMRT) in patients with prostate cancer who had undergone rectal surgery.
We retrospectively analyzed patients with prostate cancer after rectal surgery, who were definitively treated with IMRT between January 2000 and December 2019 at our institution. The planned total dose was 70-78 Gy in 2-Gy fraction, and the dose to the rectal anastomosis was limited to 70 Gy. The acute and late toxicities and survival outcomes were evaluated.
Twenty patients were included in the analysis. The median age was 71 years, with a median follow-up of 86 months. The median time from surgery to IMRT was 93.5 months. The median prostate-specific antigen value was 13.17 ng/ml. The median total dose was 74 Gy, and the median maximum dose to rectal anastomosis was 66.97 Gy. The 8-year biochemical recurrence-free and overall survival rates were 70.2% and 90.0%, respectively. The incidence rates of grade 2 acute genitourinary and gastrointestinal toxicities were 14.3% and 0%, respectively. No grade ≥ 3 acute or late toxicities were observed when the rectal anastomosis dose was limited to 70 Gy.
This retrospective analysis suggested that IMRT for patients with prostate cancer after rectal surgery may be safe and effective with rectal dose constraint of D < 70 Gy if more than 5 years have passed after surgery.

© 2022. The Author(s) under exclusive licence to Japan Society of Clinical Oncology.