Prevalence of Regional Lymph Node Metastasis of Mucosal Gastric Signet Ring Cell Carcinoma: Analysis of the Collaborative Stage Data Survey of the Korean Central Cancer Registry

<b><i>Introduction:</i></b> Patients with very early-stage gastric signet ring cell carcinoma (SRC) are eligible for minimally invasive treatment, like endoscopic submucosal dissection. However, population-based data on regional lymph node metastasis (LNM) and distant metastasis of gastric SRC are lacking. This study aimed to identify the prevalence of LNM and distant metastasis in mucosal cancer (T1a) of gastric SRC. <b><i>Methods:</i></b> The Collaborative Stage Data Survey was performed by the Korean Center of Cancer Registry between 2010 and 2015 to establish collaborative stage data of the stomach, colon, rectum, rectosigmoid junction, and breast. From the survey data, information on patients with gastric SRC was extracted for analysis. Variables including age, sex, diagnosis date, primary site, tumor size, histology, American Joint Committee on Cancer staging system scores, and Surveillance, Epidemiology, and End Results summary stage were analyzed. <b><i>Results:</i></b> A total of 1,335 (65.7%) patients had mucosal gastric SRC, and 1,189 (89.1%) patients had surgery and 134 (10%) had endoscopic treatment. Of them, 1,283 (96.1%) patients did not have regional LNM, and 52 (3.9%) patients had regional LNM and 6 (0.4%) had distant metastasis. The hazard ratios of LNM and distant metastasis were 14.98 (95% CI: 4.18–53.2) and 10.09 (95% CI: 2.30–44.17). <b><i>Conclusions:</i></b> Reginal LNM and distant metastasis occur very less in mucosal gastric SRC, but they are associated with an increased risk of cancer-related death. Even in early stage, surgery should be considered as a standard treatment of mucosal gastric SRC.