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

Abstract

Background and purposeLate 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 methodsPatients with prostate adenocarcinoma treated with curative or adjuvant RT underwent endoscopy 1year 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). ResultsThe best dosimetric predictors of grade ⩾2 telangiectasia were rectal (r) V60 Gy (p=0.014), rV70 Gy (p=0.017) and rDmean (p=0.018). Similar results were obtained for grade ⩾2 VRS. The set of rV60 Gy<34.4%, rV70 Gy<16.7% and rDmean<57.5Gy was associated with a decreased risk of grade ⩾2 telangiectasia and VRS. ConclusionsrV60 Gy, rV70 Gy and rDmean 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.