ENDOSCOPIC ULTRASONOGRAPHIC DIAGNOSIS OF DEPTH OF GASTRIC CANCER INVASION

Abstract

Diagnostic utility of endoscopic ultrasonography (EUS) for the determination of the depth of gastric cancer invasion was evaluated and tried to improve the EUS criteria for the diagnosis. Accuracy rate of the diagnosis by the traditional EUS criteria was 72% for 170 patients with gastric cancer determined by histological studies for them. Many cases overdiagnosed by the EUS were revealed to have ulcer scar with fibrosis and many of them showed tapering or smooth disruption of the third hyperechoic layer. On the other hand, many cases of correct diagnosis without ulcer had an irregular disruption of the third hyperechoic layer. The cases with highly thickening of the fourth hypoechoic layer suggested the presence of advanced cancer, however, the cases with mild thickening of the fourth hypoechoic layer were unable to evaluate of the depth of cancer invasion. In this study, new criteria was established by the addition of the degree of thickening of the fourth hypoechoic layer and shape of the third hyperechoic layer to the traditional EUS diagnostic criteria. The main improvement of new criteria are as follows ; (1) Those showing type of highly thickening of the fourth hypoechoic layer were diagnosed as subserosal or serosal cancer. (2) Those showing type of tapering or smooth disruption of the third hyperechoic layer with normal or mild thickening of the fourth hypoechoic layer were diagnosed as mucosal cancer. (3) In the cases with mild thickening of the fourth hypoechoic layer, those showing type of irregular disruption of the third hyperechoic layer were diagnosed as muscularis propria cancer and those showing type of thickening of the third hyperechoic layer without disruption were diagnosed as subserosal or serosal cancer. The total accuracy rate by new criteria was improved up to 81%, accuracy rate of mucosal cancer was especially improved up from 59% to 84%.