Comparison of the survival difference between AJCC 6th and 7th editions for gastric cancer patients

The AJCC 7th edition changes the classification of T- and N-factors and the TNM stage of gastric cancer. We evaluated its prognostic impact.

From December 1987 to December 2006, a total of 1,380 patients underwent curative surgery for gastric cancer at the Department of Surgery, Taipei Veterans General Hospital, with a retrieved lymph node number ≥ 15. Survival was compared for disease classified according to the AJCC 6th and 7th editions.

There is a significant difference in 5-year survival between T2 and T3 gastric cancer classified according to the AJCC 7th edition (75.2 vs. 54.9%, p < 0.001), as well as between N1 and N2 (71.4 vs. 44.1%, p < 0.001). Although patients with N3a had a better 5-year survival than did those with N3b (27.6 vs. 11.3%, p < 0.001), the N3 categories were combined and not applied in the TNM stage in the 7th edition. Multivariate analysis using Cox's proportional hazards model with a forward logistics regression stepwise procedure demonstrates that age, N category of 6th edition, and T and N categories of 7th edition are independent prognostic factors; however, T category of 6th edition is no longer significant. Furthermore, the discriminative power of survival difference between each TNM stage seems to be comparable between the 6th and 7th editions.

The AJCC 7th edition provides a more stratified survival difference in staging of gastric cancer. Future division of N3a and N3b in the classification of the TNM stage is recommended.