[Endoscopic sonography in cancer diagnosis].

Endoscopic ultrasonography (EUS) is the method to investigate sonographically tissue architecture by intraluminal scanning using the endoscope mounted a mechanical or electronic scanning device. The method is very effective in visualizing GI tract as well as organs present in the vicinity of digestive hollow organs as high resolution sonographic images. The method can be applied also to investigate various intraperitoneal organs, especially the liver by means of sonolaparoscopy. The most obvious application of the method is the staging of malignant neoplasms of the GI tracts especially of the stomach, esophagus and rectum. EUS mostly reveals five layer structure as layers different in echogenicity and it is considerably accurate to assess extents of wall involvement in malignancy, ulceration and inflammation of the digestive tract. It is effective in differentiating between carcinoma and submucosal tumors simply by ultrasonic localizations of the tumor masses. Involvement of regional lymph-nodes can be assessed is fairly accurate thus giving precise indication in the treatment, either medical or surgical means. Agreements between EUS staging of gastric cancer and histopathological determination were considerably accurate over various stages of gastric cancer, however, the presence of concomitant ulceration sometimes caused slight over-reading on the side of EUS. Laparoscopic sonography has also proven a considerable accuracy over existing imaging methods in terms of differential diagnosis of minute liver masses. These results seem to support the view that EUS, which is only slightly invasive, has opened up new area in cancer diagnosis, especially in the diagnosis of deeply sitting neoplasms, in which other sophisticated imaging technique are not yet available.