Acute and Late Rectal Toxicity Following Hypofractionated Radiotherapy in Patients With Prostate Cancer: Results of a Prospective Study

Background/Aim: Previous randomized clinical trials have shown that moderate hypofractionation has a non-inferior or even superior efficacy to conventionally fractionated external beam radiation therapy (EBRT) in low and intermediate-risk prostate cancer. We herein aimed to evaluate the acute and late gastrointestinal (GI) toxicity of hypofractionated radiotherapy (HRT) in a real-world setting. Patients and Methods: Patients with intermediate-risk prostate adenocarcinoma eligible to receive HRT were prospectively enrolled. All patients were submitted to rectoscopy after completion of HRT, every three months after radiotherapy for the first year and every six months for the second year. Toxicity events were classified as acute, when presenting during radiotherapy or within the first three months following its completion, and as late when appearing three months to three years post-HRT. Results: Twenty prostate cancer patients participated in this study and received 22 sessions of HRT (5 sessions a week; 2.75 Gy per session) and an overall dose of 60.5 Gy. None of our patients developed acute GI toxicity; late GI toxicity (RTOG/EORTC grade 3 rectal bleeding) was observed in 1 patient only (1/20, 5%), at 6- and 12-months post-HRT. No rectal mucosa damage was observed on follow-up rectoscopy in the acute phase in any of our patients; five patients (5/20, 25%) developed late telangiectasias. Vienna retroscopy score (VRS) was 1 in 4/5 patients (80%) and 2 in 1/5 (20%). Conclusion: Minimal radiation-induced rectal mucosal damage was observed in our patient population, and only as a late event, further attesting to the safety of HRT in this setting.