Evaluation of the new American Joint Committee on Cancer/International Union Against Cancer classification of lymph node metastasis from gastric carcinoma in comparison with the Japanese classification

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Abstract
BACKGROUND A new system for the classification of gastric carcinoma, based on the number of metastatic lymph nodes, has been adopted by the current American Joint Committee on Cancer/International Union Against Cancer (AJCC/UICC) TNM system (1997). The purpose of this study was to evaluate the rationality of this classification in comparison with the Japanese classification, which is based on the location of positive lymph nodes. METHODS The authors analyzed 587 patients who underwent clinically curative gastrectomy with D2 lymphadenectomy for gastric carcinoma and each had 15 or more lymph nodes histologically examined from 1982 to 1992. Multivariate analysis with the Cox proportional hazards model was carried out to determine which classification was more effective. RESULTS Within the pN1 or pN2 category of the new AJCC/UICC system, no significant difference in the survival rates existed between n1 patients and n2 patients of the Japanese classification. On the other hand, the survival rates significantly decreased, in the order of pN1, pN2, and pN3 (from greatest to smallest decrease), within the n1 and n2 categories. In multivariate analysis, lymph node involvement by the AJCC/UICC classification was selected as the most significant prognostic determinant, whereas the Japanese lymph node classification was not significantly prognostic. When survival rates were calculated within the pT1, pT2, and pT3–4 categories, no differences existed between pN0 and pN1. There was some discrepancy between the survival rate for each pT and pN category and the corresponding stage. CONCLUSIONS The new AJCC/UICC classification for lymph node involvement of gastric carcinoma is basically acceptable and considered superior to the Japanese classification. Further analysis involving a greater number of cases may be necessary to confirm the applicability of this staging system. Cancer 1999;86:553–8. © 1999 American Cancer Society.