Clinical predictors of pathological good response in locally advanced rectal cancer.

PURPOSE The aim of this study was to identify the clinical predictors of pathological good response (PGR) after neoadjuvant chemoradiotherapy (nCRT) in locally advanced rectal cancer (LARC) to clarify the indications for local excision. METHODS AND MATERIALS A total of 173 patients with LARC (cT3-4/N +) who were treated with nCRT followed by surgery were enrolled in our retrospective study. Patients were categorized into two groups according to the different tumor responses of surgical pathology. Stage ypT0-1N0 was defined as the group with PGR, and stage ypT2-4N0/ypTanyN + was the defined as the pathological poor response (PPR) group, and the potential predictors were compared. RESULTS Of 173 patients, PGR was achieved in 57 patients (32.95%). The distance from the inferior margin of the tumor to the anal verge, cT classification, pretreatment carcinoembryonic antigen (CEA) and the interval from the end of radiation to surgery were correlated with pathological response. In the multivariate analysis, the distance from anal verge < 5 cm (OR = 0.443, p = 0.019), pretreatment CEA < 5 ng/mL (OR = 0.412, p = 0.015) and the interval from the end of radiation to surgery ≥ 84 days (OR = 2.652, p = 0.005) were independent predictors of PGR. CONCLUSIONS The distance from the inferior margin of the tumor to the anal verge, pretreatment CEA and the interval from the end of radiation to surgery were significant predictors of PGR in LARC. A prospective study is needed to further validate these results in the future.