Evaluation of the seventh AJCC TNM staging system for gastric cancer: a meta-analysis of cohort studies.

The AJCC seventh edition TNM classification for gastric cancer was released in 2010 and included major revision. Large-volume gastric cancer centers have evaluated the prognostic significance of the new system and obtained paradoxical results. The authors performed a meta-analysis of these studies to evaluate the new classification. Fifteen eligible studies with 38,972 patients were included in the analysis. Hazard ratios (HRs) and associated 95 % confidence intervals were extracted from identified studies. The primary outcome was overall survival. The HRs for the seventh edition T classification and N classification were found to increase steadily and reasonably. The cumulative survival rates of the seventh edition subgroups of T classifications demonstrated obvious differences; meanwhile, the differences between subgroups of N classifications including N3a and N3b categories were also significant. The 5-year survival rates according to the seventh edition TNM staging system were 94.71 % (stage IA), 88.72 % (stage IB), 80.45 % (stage IIA), 67.24 % (stage IIB), 53.68 % (stage IIIA), 37.56 % (stage IIIB), and 21.26 % (stage IIIC), respectively. The results of this study indicate that the seventh edition of the TNM classification was considered valid, although further evaluation was needed for N3a and N3b categories.