Accuracy of high-frequency catheter-based endoscopic ultrasonography according to the indications for endoscopic treatment of early gastric cancer

Background and Aim: The development of endoscopic treatment, such as endoscopic submucosal dissection, extends the indications for endoscopic resection in patients with early gastric cancer (EGC). Endoscopic ultrasonography (EUS) is the first-choice imaging modality for determining the depth of invasion of gastric cancer. The aim of the present study was to prospectively assess the accuracy of EUS for determining the depth of EGC, according to the accepted/extended indications. Methods: We prospectively included a total of 181 lesions in 178 patients, with an endoscopic diagnosis of EGC, who underwent EUS for staging the depth of tumor invasion using a 20-MHz catheter probe. We investigated the accuracy of EUS for determining the depth of endoscopically-suspected EGC and then analyzed the difference in the accuracy of EUS according to the accepted/extended indications. Results: Of the 178 patients, five patients were dropped because of the absence of final histological results. For the 176 lesions in 173 patients, the accuracy of EUS assessment for the depth of tumor invasion was 80.7% (142 of 176 lesions). The accuracy of EUS for the lesions with accepted indications and with extended indications was 97.6% (40 of 41 lesions) and 83.6% (46 of 57 lesions), respectively (P = 0.040). Of the lesions with extended indications, the accuracy of EUS decreased especially for the lesions with ulceration and those with minute submucosal invasion (79.2% and 42.9%, respectively). Conclusions: The accuracy of EUS for the lesions with the extended indications was lower than that for the lesions with the accepted indications. In particular, lesions with ulceration and minute submucosal invasion should be carefully considered prior to endoscopic treatment by pretreatment EUS staging.