A new method of endoscopic ultrasonography for determining lesion depth in early gastric cancer

Atsushi Mitsunaga1, Tomoko Tagata1, Tetsuya Hamano1, Honami Teramoto1, Izumi Shirato2, Miho Shirato2, Takayoshi Nishino21Department of Endoscopy, 2Department of Gastroenterology, Tokyo Women's Medical University Yachiyo Medical Center, Yachiyo, Chiba, JapanPurpose: Endoscopic submucosal dissection (ESD) is recommended for the treatment of early gastric cancer (EGC) diagnosed as differentiated adenocarcinoma <30 mm in diameter with depth of invasion into the submucosa ≤500 μm (ie, submucosal [SM] 1 cancer). It is therefore important to develop a method for the differential diagnosis of SM1 (invasion depth ≤500 μm) from SM2/3 cancers (invasion depth >500 μm), of which the latter cannot be treated with ESD. To aid in differential diagnosis, a prospective study was conducted to establish a new diagnostic method for more accurate differential diagnosis by measurement of lesion depth using endoscopic ultrasonography (EUS) as a preoperative diagnostic modality.Patients and methods: The lesions of 92 EGC patients were examined by EUS prior to ESD or surgery to identify and measure the area with the most thickened submucosal layer. A pathological examination of the entire resected lesion was conducted to diagnose depth of invasion and histological type of EGC. Using receiver operating characteristic analysis, a cut-off threshold of 2.2 mm for submucosal thickness was calculated for differential diagnosis of mucosal (M)-SM1 from SM2/3 cancers.Results: By using thickness of the submucosal layer as measured by EUS and a cut-off threshold of 2.2 mm, M-SM1 could be distinguished from SM2/3 cancer with 98.6% accuracy, 93.2% sensitivity, and 94.7% specificity.Conclusion: Using the thickness of the submucosal layer of an EGC lesion as determined by EUS and a cut-off threshold of 2.2 mm is a highly accurate means of differentiating M-SM1 from SM2/3 cancers when determining the best means of EGC treatment.Keywords: adenocarcinoma, depth of invasion, early gastric cancer, endoscopic submucosal dissection, endoscopic ultrasonography, submucosal thickness