Tumor Volume Predicts for Pathological Complete Response in Rectal Cancer Patients Treated With Neoadjuvant Chemoradiation

Purpose/Objective(s) Currently, neoadjuvant chemoradiation (CRT) followed by total mesorectal excision is a standard treatment for patients with stage II and III rectal cancer. However, non-operative management of rectal cancer is an emerging approach to allow patients to preserve their anal sphincter. Factors that may help identify patients most likely to have a pathological complete response (pCR) would be helpful for physicians and patients considering a non-operative approach. Materials/Methods A total of 377 patients from our institution who had clinical stage II or III rectal cancer treated with neoadjuvant chemoradiation were included in the analysis. Patients were grouped based on their pCR status. Clinical parameters including overall stage, gross tumor volume (GTV), and radiation dose were analyzed by univariate and multivariate analysis, with pCR being the dependent variable. A Receiver Operator Characteristic (ROC) curve was generated in order to identify a tumor volume cutoff with the highest sensitivity for predicting pCR. Results The cohort had a median age at diagnosis of 61 years, 68% were male, and 85% presented with stage III disease. 68 of the 377 patients (18%) included in our analysis achieved pCR. A tumor volume of Conclusion Our analysis identified a GTV volume of