Assessment of lymph node micrometastasis in early gastric cancer in relation to sentinel nodes

The development of endoscopic resection and reduced surgical procedures has progressed in recent years. Lymph node micrometastases can be cited as one of the problems with reduced operations. In this study, we investigated clinicopathological findings and sentinel lymph nodes (SNs) for associations with micrometastases. We discuss the indications for endoscopic mucosal resection (EMR), reduced surgery, and sentinel node navigation surgery (SNNS) based on the results.

Immunostaining with anti-cytokeratin antibodies was used as the method of exploring for micrometastases. Comparisons and assessments were made in regard to the presence or absence of micrometastases and various clinicopathological factors.

The relationship between the clinicopathological factors and micrometastases was investigated in 120 patients with pT1pN0 gastric cancer. Significant differences in depth of invasion (mucosal [m] versus submucosal [sm]) and histological type (differentiated versus undifferentiated) were observed in both univariate analysis and multivariate analysis. Micrometastases were observed in 32% of the sm cancers, and they were observed in group 2 lymph nodes (no. 7) in 8%. They tended to be more common in the undifferentiated type. The micrometastatic lymph nodes were restricted to blue nodes (BNs) and lymph nodes within the dye flow area of patent blue (used intraoperatively explore for SNs).

It is considered that the indications for current EMR and reduced surgery in early gastric cancer are valid from the standpoint of micrometastases. But if the SNNS that has been studied in recent years is introduced, the lymphatic basin dissection method seems valid only if the case is s-pN0 early cancer.