Classification of lymph node metastases from carcinoma of the stomach: Comparison of the old (1987) and new (1997) TNM systems

The pN classification of gastric cancer is currently based on be distance o f metastatic nodes from the primary tumor (TNM-1987). The UICC (Union Inter nationale Contre le Cancer) has recently proposed a new classification syst em based on the number of the involved nodes (TNM-1997). The present prospe ctive study is aimed at verifying whether the two classifications (1) assig n approximately a similar rank to individual patients and (2) give comparab le prognostic information. The Cox regression model was used to evaluate th e prognostic significance of either the distance or the number of positive nodes, controlling for sex, age, site, histology and depth of tumor invasio n, in a group of 175 patients who underwent curative surgery for gastric ca ncer from March 1988 to October 1997. Among the patients classified as N1 a nd N2 according to TNM-1987, 81.8% (36/44) and 35.8% (19/53), respectively, were coded as N1 and N2 by the new classification, The survival probabilit ies of N1 and N2 categories were similar in both classifications. The N2 ca tegory of TNM-1987 comprised also 10 eases with >15 positive nodes (N3 cate gory of TNM-1997), who presented a large excess mortality (RR = 35.14 with respect to N0). When the site and number of positive positive nodes are com bined in a new variable, both appear to be important from a prognostic poin t of view. Both anatomic location and number of nodes with metastasis are i mportant predictors of survival in gastric cancer patients. Caution should be used when replacing the old classification with the new one, as they gro up patients in a different way.