Diagnostic utility of 20-megahertz linear endoscopic ultrasonography in early gastric cancer

Background: Because of the widespread endoscopic treatment of early gastric cancer (EGG), accurate pretherapeutic staging of the invasion depth of EGC differentiating those limited within the mucosa from cancers invading the submucosa has become important. Methods: We staged the depth of tumor invasion of 47 lesions of EGC using 20 MHz linear endoscopic ultrasonography (EUS). The EUS probe was introduced via the instrument channel of a standard endoscope. Results: The accuracy of 20 MHz EUS in staging the mucosa or submucosa was 72.3%. There was 19.1% overstaging, 2.1% understaging, and 6.4% indeterminant. The principal causes of errors were inflammation associated with ulcers, benign cystic glands in the submucosal layer, and attenuation of the high-frequency ultrasound beam. Conclusions: 20 MHz EUS is useful in the pretherapeutic staging of EGG.