PRETREATMENT STAGING OF ENDOSCOPICALLY EARLY GASTRIC-CANCER WITH A 15MHZ ULTRASOUND CATHETER PROBE

Background: The usefulness of and problems associated with an ultrasou nd catheter probe in the pretreatment staging of endoscopically early gastric cancer remain unexplored. Methods: Endoscopic: ultrasonography using a 15 MHz catheter probe of 2.6 mm diameter was performed in a p rospective study to determine the pretherapy staging of endoscopically early gastric cancer in 78 patients. The results of the ultrasound im ages were compared with the histologic findings of the specimens obtai ned by endoscopic mucosal resection or surgical resection. Results: Th e accuracy of the catheter probe for depth of invasion of endoscopical ly early gastric cancers was 67% (52 of 78 patients). The accuracy in determining depth of invasion in relation to endoscopic type was signi ficantly higher for the elevated type (91%) than for the depressed typ e of early cancer (56%) (p < 0.01). The staging accuracy classified by histologic type was significantly higher for differentiated (86%) tha n for undifferentiated (18%) cancer (p < 0.01). Staging accuracy decre ased as tumor size increased. The accuracy, sensitivity, and specifici ty for nodal staging were 80%, 17%, and 90%, respectively. Conclusions : A 15 MHz ultrasound catheter probe is most useful for determining de pth of invasion when the tumor is histologically differentiated and en doscopically of the small elevated type early gastric cancer, but it i s unreliable in the diagnosis of metastatic lymph nodes.