Risk factors for lymph node metastasis of submucosal invasive differentiated type gastric carcinoma: clinical significance of histological heterogeneity.

BACKGROUND: The use of endoscopic resection for submucosal invasive gastric carcinoma (Sm-ca) with histologically differentiated type has been expected. However, the treatment criteria remain controversial. The purpose of this study was to clarify the relationship between lymph node metastasis and the histologic features of differentiated Sm-ca.
METHODS: The clinicopathologic features of 35 patients with node-positive differentiated Sm-ca were compared with those of 221 patients with node-negative differentiated Sm-ca by multivariate analysis with logistic regression. To clarify the metastatic behavior of differentiated Sm-ca, we examined mucin-histochemical expression and immunohistochemical staining, using Ki-67, p53, and c-erbB2.
RESULTS: The rate of lymph node metastasis was significantly higher in differentiated Sm-ca with histological heterogeneity (combined differentiated type, with poorly differentiated component) than in that without histological heterogeneity (27% vs 7%; P < 0.001). Multivariate analysis revealed that lymphatic vessel invasion was the most significant determinant (odds ratio, 8.68) for lymph node metastasis. Histological heterogeneity (odds ratio, 3.88) was next, followed by papillary adenocarcinoma (odds ratio, 3.28), and submucosal invasion level (odds ratio, 2.34). The mean value of the Ki-67 labeling index for node-positive differentiated Sm-ca was higher than that of node-negative differentiated Sm-ca (47% vs 39%; P < 0.05).
CONCLUSIONS: When the extension of endoscopic surgery to differentiated Sm-ca is considered, this therapeutic technique should be limited to the differentiated type of Sm-ca without histological heterogeneity. The Ki-67 labeling index provides useful information for identifying those patients with a high risk of lymph node metastasis.