Endoscopic ultrasonography for diagnosis of submucosal invasion in early gastric cancer.
Endoscopic ultrasonography (EUS) is considered to be useful for deciding the treatment course for early gastric cancer. To determine reliable indications suggesting submucosal tumor invasion, we retrospectively analyzed EUS images of the hyperechoic third layer, which corresponds to the submucosa. The subjects enrolled in this study were 75 patients, with 78 gastric cancers (diagnosed as mucosal cancer without ulcerous changes on endoscopy and as histologically differentiated adenocarcinoma on biopsy), who were also examined by EUS. We retrospectively classified EUS features of the third layer (submucosa) into five groups: (1) irregular narrowing, (2) budding sign, (3) multiple echo-free spots, (4) unclear, and (5) no changes. In endoscopically diagnosed gastric mucosal cancer, 16 of the 78 lesions were associated with histologic submucosal invasion. EUS features that were associated with a high incidence of histological submucosal tumor invasion were irregular narrowing (submucosal invasion, 60.0%) and the budding sign (85.7%), and 90.9% of lesions with either of these features had submucosal invasion of tumors when tumorous changes in the third layer exceeded 1 mm in depth. Endosonographic irregular narrowing and a budding sign of more than 1 mm in depth in the third layer are useful for the diagnosis of submucosal invasion in gastric cancers that are diagnosed as mucosal cancers without ulcerous change on endoscopy.