Limits of Clinical Restaging in Detecting Responders After Neoadjuvant Therapies for Rectal Cancer

Background: An accurate clinical restaging is required to select patients who respond to neoadjuvant chemoradiotherapy for locally advanced rectal cancer, and who may benefit from an organ preservation strategy. Objective: The purpose of this study was to review our experience with the clinical restaging of rectal cancer after neoadjuvant therapy to assess its accuracy in detecting major and complete pathological response to treatment. Design: Retrospective cohort study. Setting: This study was conducted at two high-volume Italian centers for Colorectal Surgery. Patients: We included data of all consecutive patients who underwent neoadjuvant therapy and surgery for locally advanced rectal cancer from January 2012 to July 2020. Criteria to define clinical response were no palpable mass, a superficial ulcer <2cm (major response) or no mucosal abnormality (complete response) at endoscopy, and no metastatic nodes at magnetic resonance imaging. Main outcome measures: We explored sensitivity, specificity, positive and negative-predictive values of clinical restaging in detecting complete (ypT0) or major (ypT0-1) pathological response after neoadjuvant therapy. Results: We included 333 patients; 81 (24.3%) had a complete while 115 (34.5%) had a major pathological response. Accuracy for clinical complete response and clinical major response was 80.8% and 72.9%, respectively. Sensitivity was low both for clinical complete response (37.5%) in detecting ypT0 and major clinical response (59.3%) in detecting ypT0-1. Positive-predictive value was 68.2% for ypT0 and 60.4% for ypT0-1. Limitations: Our study has the main limitation in its retrospective nature. Conclusion: Accuracy of actual clinical criteria to define complete or major pathological response is poor. Failure to achieve good sensitivity and precision is a major limiting factor in the clinical setting. Indication for rectal preservation after neoadjuvant chemoradiotherapy needs an improvement of current clinical assessment. See Video Abstract at http://links.lww.com/DCR/C63.