ENDOSCOPIC ULTRASOUND STAGING OF GASTRIC MALIGNANCY

Abstract

Endoscopic ultrasound (EUS) has been well established as a good tool for the staging of gastric malignancy. So far, it is accepted as the most accurate image study for local staging of gastric malignancy. Staging of gastric carcinoma is important for decision‐making in management and prediction of prognosis. With the power of high‐resolution imaging on gastric layering, the overall accuracy rate of T staging by EUS ranges 70–98%. For T2 tumors, however, EUS assessment is less reliable. N staging by EUS for gastric carcinoma is unsatisfactory and its accuracy rate has been reported 55–87%. However, the application of EUS should depend on whether examination will alter the choice of therapeutic methods and whether patients benefit from EUS evaluation. Among the indications, EUS staging is very important for the patients referred for local endoscopic treatment, such as endoscopic mucosal resection, endoscopic submucosal dissection or tumor ablation by argon plasma coagulation (APC) tumor ablation. EUS can provide the depth of invasion of the gastric wall, and also the longitudinal spread of lymphoma in the gastric wall. The overall accuracy rate of depth staging is 80–96%. For the metastatic lymph nodes, accuracy rate of N staging is 72–90%. EUS is also applied to restaging of gastric lymphoma after chemotherapy. Mucosa‐associated lymphoid tissue (MALT) lymphoma is a subset of B‐cell lymphoma with good prognosis and high prevalence of Helicobacter pylori infection. EUS staging of depth invasion of MALT lymphoma can predict the outcome of antimicrobial treatment. Taiwan's experience shows that lesions limited to mucosal and submucosal layers respond better after treatment than lesions with deeper infiltration, no matter if the MALT lymphoma is low‐grade or high‐grade.