Abstract
As a part of diagnostic trials using EUS in lesions of the upper digestive tract, the capacity of endoscopic ultrasonography (EUS) in determining the depth of cancer invasion was discussed. Eight patients with esophageal cancer and 78 patients with gastric cancer, including 58 with gastric cancer in which histological finding were also obtainable, were examined by EUS. The upper digestive tract was displayed by EUS as a 5-layers structure, namely, the 1st hyperechoic & the 2nd hypoechoic layers containing of mucous, mucosa and mucosal muscle, the 3rd hyperechoic layer as a submucosal layer, the 4th hypoechoic layer as a proper muscular layer and the 5th hyperechoic layer containing of subserosal layer and serosa. Based on the changes in these layers structure on scans, the depth of cancer extension could be determined. In the cancers confined to the mucosa (m cancer), no echographic changes were observed in any layers except the irregularity of the 1st and 2nd layers. In the cancers involving the submucosa (sm cancer), the sm layer was exhibited as a irregular layer without interruption. The cancers extending into the proper muscle layer (pm cancer) produced interruption at the sm layer. Interruption at the 3rd and 5th layers with highlevel echo was observed in the cancers extending into the subserosa or deeper tissues. In the cancers complicated by ulcer, the differentiation between the interruption caused by a tumor and that by an ulcer was possible based on the morphological appearance in the sm layer. That is, an abrupt interruption of the sm layer was caused by a malignant invasion, on the other hand, an ulcerative change showed a tapering interruption of the sm layer. Gastric cancer with scirrhus invasion was presented characteristic images by EUS, namely, swelling and destruction of all layers, especially of the sm layer. Advanced cancers were correctly differentiated from early cancers by the presence of the interruption of the sm layer in 54 of 58 cases (93.1%). Furthermore, a correct distinction of the cancer extending into the m, sm, pm and ss or deeper tissues was made in 33/41 cases (80.5%).Our result showed the usefullness of EUS in determining the depth of cancer invasion.
