Instrumental clinical restaging, pathological evaluation, and tumor regression grading: how to assess the response to neoadjuvant chemoradiotherapy for rectal cancer

Introduction The object of neoadjuvant chemoradiotherapy regimens is a downstaging or downsizing of advanced rectal tumor to increase the rate of curative resection and reduce loco-regional failure. A reliable method of assessing response to adjuvant therapies is required to help standardize the assessments of new multimodality therapies. The purpose of this study was to evaluate the role played by tumor regression grading on the evaluation of pathological response to chemoradiotherapy, compared with both the predicting value of the clinical response to neoadjuvant therapy and pathologic response evaluation.