Multi‐institutional validation of the 8th AJCC TNM staging system for gastric cancer: Analysis of survival data from high‐volume Eastern centers and the SEER database

Background The clinical relevance and general applicability of the 8th American Joint Committee on Cancer TNM gastric cancer staging system vs the 7th version have not been examined using datasets from both the East and West. Methods Patients (n = 29 984) treated for gastric adenocarcinoma at two high‐volume centers (Severance Hospital [SH] and Gangnam Severance Hospital [GSH]) in Korea and data from the Surveillance, Epidemiology, and End Results (SEER) database were retrospectively analyzed. Survival curves, the performance of tumor staging, and the homogeneity of modified subgroups were compared. Results Minute changes were noted in the stage IIB subgroup; most changes were noted in stage III. Applying the 8th staging system facilitated better prediction of survival than applying the 7th version for SH data according to the log‐rank test, C‐index, and AIC (8444.5 vs 9263.8, 0.796 vs 0.798, and 104152 vs 103909, respectively). Its performance was also superior for GSH and SEER data. In a subgroup analysis of stages IIB to IIIC in SH, GSH, and SEER data, the 8th staging system showed similar or more homogeneous survival for each sub‐classification than the 7th version. Conclusion Compared with the 7th gastric cancer staging system, the newer version more accurately predicted prognosis and stratified subgroups more homogeneously.