Comparison of staging between the old (6th edition) and new (7th edition) TNM classifications in advanced gastric cancer.

Background: The aims of the present study were to compare staging between the old (6th edition) and new (7th edition) TNM classifications, and to evaluate the prognostic impact of extended lymph node dissection according to the new nodal staging in advanced gastric cancer.

Methods: A total of 609 patients with advanced gastric cancer who had undergone curative gastric resection combined with extended lymph node dissection were enrolled in the present study. Survival curves were analyzed according to staging based on the TNM 6th and 7th editions and the Japanese Classification of Gastric Carcinoma (JCGC) 14th edition.

Results: The 5-year survival rates and the consecutive stage survival with no significant differences were: IB 88%; II 74%; IIIA 53%; IIIB 39%; and IV 18% (IIIA vs. IIIB, p=0.1307) by the TNM 6th edition; IB 94%; IIA 85%; IIB 71%; IIIA 68%; IIIB 48%; IIIC 23%; and IV 13%; (IIB vs. IIIA, p=0.7665; IIIC vs. IV, p=0.4156) by the TNM 7th and JCGC 14th editions; N0 85%; N1 70%; N2 46%; N3 18%; and M1 13%; (N3 vs. M1, p=0.8640) by the TNM 6th edition; and N0 85%; N1 80%; N2 61%; N3a 46%; N3b 18%; and M1 13%; (N0 vs. N1, p=0.2735; N2 vs. N3a, p=0.0663; N3b vs. M1, p=0.8640) by the TNM 7th and JCGC 14th editions.

Conclusions: The new classification according to the TNM 7th and the JCGC 14th editions does not always seem to be superior to the TNM 6th edition for the prognostic stratification of stages in patients who undergo curative resection for advanced gastric cancer. An extended lymph node dissection may be effective for N0-N3a, but not for N3b and M1 stages classified according to the new TNM 7th and JCGC 14th editions.