Is pathologic tumor regression grade after neo-adjuvant chemotherapy a promising prognostic indicator for patients with locally advanced gastric cancer? A cohort study evaluating tumor regression response

Background The MAGIC trial has shown perioperative chemotherapy does significantly improve overall survival of patients with gastric and esophagogastric junction carcinoma. The approach to evaluate the effectiveness of adjuvant chemotherapy is urgent in clinical practice. Methods Totally, 264 patients with locally advanced gastric carcinoma (including esophagogastric junction carcinoma) treaded by perioperiate chemotherapy (SOX or XELOX) from May 2012 to December 2017 in our cancer center were included. Tumor response was evaluated by tumor regression grade (TRG, Mandard system) and Response Evaluation Criteria in Solid Tumor (RECIST v1.1). The clinical characteristics and the effect on survival were analyzed. Result Univariate analysis showed TRG was correlated to tumor size, Lauren classification, grade of differentiation, histological type, postsurgical T category (ypT), postsurgical N category (ypN), vascular invasion or lymphatic invasion and so on. However, only Lauren classification and ypT were independent factors for TRG. On contrary to RECIST, TRG was founded to be a prognostic factor for DFS and OS on univariate analysis. Cox proportional hazards were established to evaluate the relationship among TRG, clinical-pathological factors and survival. On multivariate analysis, the chemotherapy cycle, Lauren classification, vascular invasion or lymphatic invasion, ypN and postsurgical pathologic stage were independent factors for OS and DFS, while TRG were negatively correlated to survival. Conclusion TRG seems to be a promising prognostic indicator and it predicts the prognosis of patients with locally advanced gastric cancer after adjuvant chemotherapy more reasonably in comparisons to RECIST v1.1.