Diagnostic accuracy of EUS in the local staging of primary gastric lymphoma: results of a prospective, multicenter study comparing EUS with histopathologic stage

Background. Grade of malignancy and stage of disease are the decisive prognostic factors and therapeutic determinants in primary gastric lymphoma. It is supposed that EUS allows determination of depth of tumor infiltration and perigastric lymph node involvement, thus defining stages 11, 12, and II1. This multicenter study evaluated the accuracy of EUS in the staging of gastric lymphoma. Methods: Data from preoperative EUS procedures performed at 34 centers were compared with the histopathologic stage of resection specimens in 80 patients with newly diagnosed primary gastric lymphoma. Ten patients with stage 112 were excluded from analysis because EUS is inappropriate for the evaluation of nonregional lymph node involvement. Results: EUS correctly classified the lymphoma in 37 of 70 patients (53%). Sensitivity of EUS was as follows: stage 11, 67% (95% Cl [38%, 88%]; p = 0.01); stage 12, 83% (95% Cl [52%, 98%]; p = 0.01); and stage II1, 71% (95% Cl [49%, 87%]; p = 0.02). Conclusion: The accuracy of EUS in the local staging of gastric lymphoma has to be improved if nonsurgical treatment strategies based on the grade of malignancy and stage of the disease are to be used. Because most of the participating centers performed EUS in relatively few patients, no conclusion could be drawn with respect to accuracy in relation to EUS experience available at each center or technical considerations with respect to the types of instruments used.