Validation of seventh edition AJCC gastric cancer staging modifications

Background and Objectives The seventh edition of the AJCC has more detailed staging categories for gastric cancer than does the sixth edition. The aim of our study was to compare the prognostic accuracies of the sixth and seventh AJCC editions for gastric cancer patients. Methods We analyzed survival rates by category using the sixth and seventh editions of the AJCC in 10,060 patients with gastric cancer who had undergone gastrectomy between 1994 and 2007 at Samsung Medical Center. Results Significant differences in prognosis were seen when comparing the new stages of the seventh edition of the AJCC that are subgroups of stages IB, II, IIIA, and IV in the sixth edition. In particular, stage IV of the AJCC sixth edition is divided into stages IIB, IIIA, IIIB, IIIC and IV in the seventh edition, and the 5-year survival rates of these respective stages were 80.2%, 45.3%, 23.5%, 17.2%, and 10.1% (P<0.001). Conclusions Each category of the AJCC sixth edition has been divided into multiple stages in the AJCC seventh edition, each with a different prognosis. The newly divided subgroups from AJCC sixth edition stage IV showed more accurate outcome classification based on AJCC seventh edition staging stratification.