Endoscopic Submucosal Dissection for Early Gastric Cancers with Uncommon Histology

Endoscopic submucosal dissection (ESD) enables en bloc curative resection of early gastric cancers (EGCs) with a negligible risk of lymph node metastasis (LNM). Although ESD for EGCs with absolute and expanded indications is safe, the results differ between EGCs with specialized and common histologies. EGC with papillary adenocarcinoma is a differentiated-type adenocarcinoma. At present, it is treated with ESD according to the same criteria as other differentiated-type adenocarcinomas. The LNM rate under the current indication criteria is high, and over half of the patients who undergo ESD as a primary treatment for EGC with papillary adenocarcinoma achieve an out-of-ESD result. Gastric carcinoma with lymphoid stroma in EGC has a low LNM rate and a favorable outcome, despite deep submucosal invasion. Patients with this gastric cancer subtype may be good candidates for ESD, even with deep submucosal invasion. Large-scale prospective multi-center studies with longer follow-up periods are needed to set proper ESD criteria for these tumors. Clinicians should be aware of these disease entities and ESD should be more carefully considered for EGCs with papillary adenocarcinoma and gastric carcinoma with lymphoid stroma.