Predictive Factors for Lymph Node Metastasis in Signet Ring Cell Gastric Cancer and the Feasibility of Endoscopic Submucosal Dissection

Purpose: Endoscopic submucosal dissection has recently been practiced on a differentiated type of early gastric cancer. However, there is no clear evidence for endoscopic treatments of signet ring cell carcinoma. The aim of this study is to identify the predictive clinicopathological factors for lymph node metastasis in signet ring cell carcinoma for assisting endoscopic submucosal dissection trials. Materials and Methods: A total of 186 patients with early signet ring cell carcinoma who underwent radical curative gastrectomy between January 2001 and September 2009 were enrolled in this study. Retrospective reviews of their medical records are being conducted. Several clinicopathologic factors were being investigated in order to identify predictive factors for lymph nodes metastasis: age, gender, tumor size, type of operation, tumor location, gross type, ulceration, Lauren's classification, depth of invasion, and lymphatic invasion. Results: The lymph node metastasis rate for signet ring cell carcinoma was 4.3% (n=8). Of the 186 lesions with early signet ring cell carcinoma, 91 (48.9%) tumors were larger than 15 mm in size and 40 (21.5%) showed submucosal invasions in the resection specimens. In multivariate analysis, only the lymphatic invasion (P<0.0001) showed an association with lymph node metastasis. To evaluate cutoff values for tumor sizes in the presence of lymph node metastasis, early signet ring cell carcinomas with lymphatic invasions were excluded. In the absence of lymphatic invasion, mucosal cancer with tumor sizes < 15 mm had no lymph node metastasis. Conclusions: Endoscopic submucosal dissection can be performed on patients with early signet ring cell carcinoma limited to the mucosa and less than 15 mm.