Low impact of staging EUS for determining surgical resectability in esophageal cancer.

BACKGROUND: Although studies have shown that EUS has a high sensitivity and specificity for T and N staging, the value of EUS for staging tumors as resectable or nonresectable after CT of the chest and abdomen and US neck assessment, is largely unknown. This study was designed to assess the diagnostic value of EUS for determining resectability of esophageal cancer. METHODS: A retrospective analysis of all consecutive patients with esophageal carcinoma who underwent staging EUS, CT, and US. Tumors were considered resectable when there was no evidence of metastases or ingrowth in adjacent structures. Sensitivity, specificity, positive (PPV), and negative (NPV) predictive value of CT/US neck and CT/US neck + EUS for predicting surgical resectability were calculated. PPVs of CT/US alone and CT/US + EUS together were compared for assessing the diagnostic value of EUS. RESULTS: In total, 211 patients (155 men; mean age of 64 ± 9.4 years) were included, of which 176 (83 %) underwent all three staging investigations. Based on preoperative staging, 173 (82 %) patients were considered resectable and 38 (18 %) nonresectable. Of all 173 initially resectable patients, 145 were operated on. Of these patients, five (3.4 %) tumors were found nonresectable during surgery. Postoperative sensitivity, specificity, PPV, and NPV of CT/US and CT/US + EUS for predicting surgical resectability were 88 versus 87 %, 20 versus 40 %, 97 versus 98 %, and 6 versus 10 %, respectively. CONCLUSIONS: Although EUS adds to the specificity of preoperative esophageal cancer staging after CT chest and abdomen, and US of the neck have been performed, the overall added value of EUS is limited.

The use of hapten-modified antigens instead of solid-phase-coupled antigens in a RAST-type assay.

We have developed a modification of the solid-phase immunoassay for the detection of antibodies of specified isotype. This modified assay involves interaction of the antibody in solution with a haptenated antigen, followed by binding of the antigen-antibody complex to an anti-hapten immunoadsorbent. The antibody is subsequently detected with a suitably labelled antiglobulin reagent. The advantages of this test are: (1) The procedure is more convenient, especially in test protocols where multiple antigens are used. Because the antigens are in solution, computer-controlled dispensation of the antigens is possible. (2) The efficiency of antibody binding is increased, presumably because of the higher avidity of the antigen-antibody interaction in homogeneous solution compared to that in a heterogeneous system. Therefore, less antigen per test is required, and a solid phase with a lower capacity can be used.