Clinical predictive factors associated with pathologic complete response in locally advanced rectal cancer

Abstract Objective In this study, our aim was to identify the main predictive factors associated with pathologic complete response (pCR) to neoadjuvantchemoradiotherapy (nCRT) in patients with locally advanced rectal cancer. Methods The patients who had locally advanced rectal cancer and underwent a long-course nCRT, followed by curative surgery between January 2009 and December 2015 at two-center were included. The clinical factors associated with pCR or non-pCR were analyzed by Logistic regression. Results Two hundred and three patients were included in this study. Forty-six patients (22.7%) had pCR and 157 patients (77.3%) had non-pCR. In the univariate analysis, no smoking history, clinically negative lymp node (cN-), well-differentiated tumor, tumor size of ≤5 cm, pre-nCRT CEA level of ≤5 (ng/mL) and median interval to surgery>8 week were associated with an increased rate of pCR. No smoking history [odds ratio (OR) = 3.382, P  = .008], endoscopic tumor size of ≤5 [OR = 2.608, P  = .03], cN- [OR = 3.800, P  = .002 ], well-differentiated tumor [OR = 3.566, P  = .002 ], median interval to surgery of >8 week [OR = 2.981, P  = .014], and pre-nCRT CEA level of ≤5 (ng/mL) [OR = 3.067, P  = .008] were determined to be independent predictive factors of pCR with logistic regression model analysis. Conclusion No smoking history, cN-, tumor size of ≤5 cm, well-differentiated tumor, pre-nCRT CEA level of ≤5 (ng/mL) and median interval to surgery of >8 weeks were independent clinical predictors for pCR in rectal cancer patients treated with long course of nCRT. This factors may help clinicians predict the prognosis of patients and develop proper treatment approach.