Comparative evaluation of gastric carcinoma staging: Japanese Classification versus new American Joint Committee on Cancer/International Union Against Cancer Classification

Background: The TNM and Japanese classifications of regional lymph node spread (N categories) for gastric cancer differ, whereas the classifications of local extent (T categories) are identical. This study was designed to compare these staging systems and devise a more rational system for gastric carcinoma. Methods: A series of 1244 patients with gastric cancer were enrolled in the study. Survival rates were evaluated to clarify which aspects of each staging system (feasibility, reproducibility, and accuracy of prognostic stratification) were superior. Results: The TNM and Japanese classification systems differ in their categorizations of lymph node spread. A significant difference in survival rate was observed in lymph node metastasis classified as N1 and N2 by the Japanese classification and then subclassified by the TNM classification, although there was no significant difference in the survival in cases of lymph node metastasis classified by TNM into pN1 and pN2 and then subclassified by the Japanese classification. Among patients with M1 metastasis (number 16 a2 and b1 in Japanese classification) in the TNM classification, there was a significant difference in survival. A new classification that included the para-aortic lymph nodes (number 16 a2 and b1) as regional lymph nodes within the TNM classification provided homogeneity and an improvement in staging. Conclusions: TNM classification was more rational and homogenous than Japanese classification. New classification could lead to worldwide uniformity in the description of patients and make possible uniform interinstitutional comparisons of surgical results.