Patient-reported intestinal toxicity from whole pelvis intensity-modulated radiotherapy: First quantification of bowel dose–volume effects

Publication date: Available online 21 July 2017
Source:Radiotherapy and Oncology
Author(s): Carla Sini, Barbara Noris Chiorda, Pietro Gabriele, Giuseppe Sanguineti, Sara Morlino, Fabio Badenchini, Domenico Cante, Viviana Carillo, Marcella Gaetano, Tommaso Giandini, Valeria Landoni, Angelo Maggio, Lucia Perna, Edoardo Petrucci, Vincenzo Sacco, Riccardo Valdagni, Tiziana Rancati, Claudio Fiorino, Cesare Cozzarini
Background and purposeIntestinal toxicity is commonly experienced during whole-pelvis intensity-modulated radiotherapy (WPRT) for prostate cancer. The aim of the current study was to assess bowel dose–volume relationships for acute patient-reported intestinal symptoms of patients treated with WPRT for prostate cancer.Materials and methodsComplete data of 206 patients were available; the median dose to pelvic nodes was 51.8Gy (range 50.4–54.4, 1.7–2Gy/fr). Intestinal symptoms were assessed as changes in the Inflammatory Bowel Disease Questionnaire scores relative to the Bowel Domain (IBDQ-B) between baseline and radiotherapy mid-point/end. The 25th percentiles of the most severe worsening from baseline (ΔIBDQ-B) were set as end-points. The impact of bowel loops and sigmoid colon dose–volume/surface parameters as well as selected clinical parameters were investigated using multivariate logistic regression.ResultsAnalyses were focused on the four questions showing a median ΔIBDQ-B>0. No dose volume/surface parameters were predictive, other than ΔIBDQ5≥3 (loose stools): when grouping patients according to bowel DVHs (high risk: V20>470cc, V30>245cc, V42>110cc; low risk: all the remaining patients), a two-variable model including high-risk DVH-shape (OR: 9.3) and age (protective, OR: 0.94) was assessed. The model showed good calibration (slope: 1.003, R²=0.92) and was found to be robust after bootstrap-based internal validation.ConclusionsConstraining the bowel loops may reduce the risk of loose stools. The risk is higher for younger patients.



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