Early radiation-induced mucosal changes evaluated by proctoscopy: Predictive role of dosimetric parameters

Background and purpose: Late rectal complications are assessed according to different scoring systems. Endoscopy can provide a more sensitive estimation of early radiation damage. The aim of this paper is to investigate the correlation between dosimetric parameters and rectal mucosal changes after radiotherapy (RT). Materials and methods: Patients with prostate adenocarcinoma treated with curative or adjuvant RT underwent endoscopy 1 year after RT. Receiver operating characteristics (ROC) analysis was performed to analyze the predictive capability of the dosimetric variables in determining mucosal changes classified by Vienna Rectoscopy Score (VRS). Results: The best dosimetric predictors of grade ≥2 telangiectasia were rectal (r) V 60 Gy (p = 0.014), rV 70 Gy (p = 0.017) and rD mean (p = 0.018). Similar results were obtained for grade ≥2 VRS. The set of rV 60 Gy < 34.4%, rV 70 Gy < 16.7% and rD mean < 57.5 Gy was associated with a decreased risk of grade ≥2 telangiectasia and VRS. Conclusions: rV 60 Gy, rV 70 Gy and rD mean were the strongest predictors of rectal mucosal alterations. In-depth analysis is required to correlate each mucosal alteration with late rectal toxicity in order to suggest early proctoscopy as surrogate end-point for rectal late toxicity in studies aimed at reducing this important complication. © 2011 Elsevier Ireland Ltd. All rights reserved.