Indication for endoscopic mucosal resection in early signet ring cell gastric cancer

Background: The aim of this study was to compare the clinicopathological characteristics of an early signet ring cell carcinoma (SRC) with an early undifferentiated carcinoma (mucinous, poorly differentiated adenocarcinoma) and early differentiated carcinoma (well or moderately differentiated tubular adenocarcinoma, papillary adenocarcinoma) and find indications for endoscopic mucosal resection (EMR) in early SRC. Methods: 1520 patients with early gastric cancer (EGC), who underwent a curative gastrectomy, were analyzed retrospectively. Among them, 388 patients with SRC were compared with 253 patients with undifferentiated carcinoma (UDC) and 879 with a differentiated carcinoma (DC). Results: SRC was more common in young female patients than UDC. SRC had a tendency to be confined to the mucosa, with smaller size than UDC. The lymph node metastasis rate for SRC was lower than that for UDC, but similar to that of DC. Multivariate analysis revealed lymph node metastasis (LNM) to be associated with the depth of invasion, tumor size, histological type, and lymphatic involvement. SRC had no LNM in the case of a mucosal tumor, smaller than 2cm, and in the absence of lymphatic involvement. The prognosis of SRC was more favorable than UDC. Conclusions: Early SRC has different characteristics from early UDC. In view of the lower rate of lymph node metastasis and better prognosis, we suggest that EMR can be performed on patients with early SRC limited to the mucosa, less than 2cm in size, and with no lymphatic involvement.