Development and validation of an MRI-based model to predict response to chemoradiotherapy for rectal cancer

Publication date: Available online 31 January 2018
Source:Radiotherapy and Oncology
Author(s): Philippe Bulens, Alice Couwenberg, Karin Haustermans, Annelies Debucquoy, Vincent Vandecaveye, Marielle Philippens, Mu Zhou, Olivier Gevaert, Martijn Intven
Background and purposeTo safely implement organ preserving treatment strategies for patients with rectal cancer, well-considered selection of patients with favourable response is needed. In this study, we develop and validate an MRI-based response predicting model.MethodsA multivariate model using T2-volumetric and DWI parameters before and 6 weeks after chemoradiation (CRT) was developed using a cohort of 85 rectal cancer patients and validated in an external cohort of 55 patients that underwent preoperative CRT.ResultsTwenty-two patients (26%) achieved ypT0-1N0 response in the development cohort versus 13 patients (24%) in the validation cohort. Two T2-volumetric parameters (ΔVolume% and Sphere_post) and two DWI parameters (ADC_avg_post and ADCratio_avg) were retained in a model predicting (near-)complete response (ypT0-1N0). In the development cohort, this model had a good predictive performance (AUC = 0.89; 95% CI 0.80–0.98). Validation of the model in an external cohort resulted in a similar performance (AUC = 0.88 95% CI 0.79–0.98).ConclusionAn MRI-based prediction model of (near-)complete pathological response following CRT in rectal cancer patients, shows a high predictive performance in an external validation cohort. The clinically relevant features in the model make it an interesting tool for implementation of organ-preserving strategies in rectal cancer.



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