Ratio of Involved Lymph Nodes to Resected Lymph Nodesas a Prognostic Factor of Gastric Cancer

Lee, Joo Ho; Kim, Soo Jin; Yu, Hang Jong; Yang, Han Kwang; Kim, Jin Pok

Abstract

The status of metastasis to the regional lymph nodes has been considered to be a major prognostic factor of gastric cancer along with the depth of invasion. So far, the extent of lymph node metastasis has mainly been described by the anatomic location of the involved lymph node, which is an artificial classification. Therefore, a quantitative system such as the number or the ratio of involved lymph nodes emerges as a simple and objective assessment tool. This retrospective study evaluated the prognostic significance of the ratio of involved lymph nodes to resected lymph nodes as an indicator of the status of lymph node metastasis compared to the number of involved lymph nodes in gastric cancer. Five thousand two hundred seventeen consecutive cases of resectable gastric cancer treated at the Department of Surgery, Seoul National University Hospital from 1986 to 1995, were reviewed. Among them, 170 cases with unreliable pathologic reports and 476 cases with less than 15 isolated lymph nodes were excluded to minimize the stage migration phenomenon and to increase the creditability of the ratio, so finally 4571 cases were evaluated. The distributions of the number of cases and the 5-year survival rates were analyzed in a two-dimensional matrix with the ratio of the number of involved to resected lymph nodes on one axis and either the number of involved lymph nodes or the number of resected lymph nodes on the other axis. The other clinicopathologic variables were also evaluated for their prognostic values. The overall 5-year survival rate was 62.4%. The mean number of resected lymph nodes was 4.1(15~168) and the mean number of involved lymph nodes was 5.7. The ratios of involved lymph nodes were evenly distributed in the two matrices and had significant prognostic value in both the involved lymph node matrix and resected lymph node matrix. Age, sex, type of operation, R-category, tumor location, Borrmann type, tumor size, histologic differentiation, Lauren`s classification, depth of invasion, number of involved lymph nodes, ratio of involved lymph nodes to resected lymph nodes, distant metastasis, perineural invasion, lymphatic invasion, and vascular invasion and prognostic significance in univariate analysis and multivariate analysis performed with the above factors revealed that R-category, depth of invasion, and ratio of involved lymph nodes to resected lymph nodes were the independent significant prognostic factors. In the situation where a radical lymph node dissection is performed as the standard operation for gastric cancer, the ratio of involved lymph nodes to resected lymph nodes has a more comprehensive and accurate prognostic value than the number of involved or resected lymph nodes, and it should be considered as an estimate of the nodal status in gastric cancer.