Prospective evaluation of EUS versus CT scan for staging of ampullary cancer

BackgroundMalignancies of the biliary and pancreatic systems are associated with a poor prognosis. However, ampullary cancer carries a better prognosis and is often diagnosed when curative treatment is still possible. Accurate staging is important for the determination of the most appropriate treatment option.Objectives(1) To determine the test performance characteristics of EUS and CT in loco-regional staging of ampullary neoplasms, and (2) to determine the impact of CT scan results on the test performance characteristics of EUS.Design and SettingProspective single-arm intervention study performed in 2 academic hospitals.Results and Main Outcome MeasurementsThirty-seven patients were screened and 33 staged with EUS and CT. A total of 27 patients (13 men; mean age, 69.5 years; mean serum bilirubin level, 12.6 mg/dL) with locally advanced disease completed the protocol with EUS and CT and underwent surgical resection. Tumor classifications were as follows: 2 patients (7.4%), T1 tumors; 13 patients (48.1%), T2 tumors; and 12 patients (44.4%), T3 tumors, as per surgical pathology. Seventeen tumors (62.9%) were classified as N0 and 10 (37.1%) as N1. The difference in proportion of correct tumor (74.1% vs 51.8%; P = .15, 95% CI, -0.06-0.50) and lymph node (81.4% vs 55.5%; P = .07, 95% CI, -0.01-0.53) staging by EUS and CT, respectively, was not statistically significantly different. However, the strength of tumor (kappa 0.51 vs 0.11) and nodal (kappa 0.59 vs 0.05) agreement with pathology was statistically significantly higher for EUS than for CT (P < .05). EUS was more sensitive and specific than CT for tumor and nodal staging, and the association of CT to EUS data did not improve the final test accuracy.LimitationLow number of T1 tumors.ConclusionsEUS is an accurate diagnostic test and exhibits a high level of agreement with surgical pathology. CT findings do not improve the test performance characteristics of EUS. Therefore, the evaluation for metastatic disease should not be compromised by CT protocols that aim to perform tumor and nodal staging. Further studies to determine the role of specialized CT protocols in patients with ampullary malignancies are needed.