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

BACKGROUND. A new system for the classification of gastric carcinoma, based on the number of metastatic lymph nodes, has been adopted by the current A merican Joint Committee on Cancer/International Union Against Cancer (AJCC/ UICC) TNM system (1997). The purpose of this study was to evaluate the rati onality of this classification in comparison with the Japanese classificati on, which is based on the location of positive lymph nodes. METHODS. The authors analyzed 587 patients who underwent clinically curativ e gastrectomy with D2 lymphadenectomy for gastric carcinoma and each had 15 or more lymph nodes histologically examined from 1982 to 1992. Multivariat e analysis with the Cox proportional hazards model was carried out to deter mine which classification was more effective. RESULTS. Within the pN1 or pN2 category of the new AJCC/UICC system, no sig nificant difference in the survival rates existed between n1 patients and n 2 patients of the Japanese classification. On the other hand, the survival rates significantly decreased, in the order of pN1, pN2, and pN3 (from grea test to smallest decrease), within the n1 and n2 categories. In multivariat e analysis, lymph node involvement by the AJCC/UICC classification was sele cted as the most significant prognostic determinant, whereas the Japanese l ymph node classification was not significantly prognostic. When survival ra tes were calculated within the pT1, pT2, and pT3-4 categories, no differenc es existed between pN0 and pN1. There was some discrepancy between the surv ival 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 J apanese classification. Further analysis involving a greater number of case s may be necessary to confirm the applicability of this staging system. Can cer 1999;86:553-8. (C) 1999 American Cancer Society.