© 2007 American Thoracic Society
It's All About US: (E)US, (EB)US, and Their US(age)From the Authors:As reported in our recent article, we evaluated the diagnostic yield of transesophageal ultrasound-guided fine needle aspiration (EUS-FNA) in suspected lung cancer and compared the accuracy of staging of EUS-FNA with that of the computed tomography (CT) scan (1). The study was not designed to compare diagnostic yield of EUS-FNA and bronchoscopy. Since EUS-FNA, as a first diagnostic test, was successful in achieving the diagnosis in 70% of cases, bronchoscopy was required in only a small number of cases. Though a prospective randomized study of EUS versus bronchoscopy would determine whether diagnostic yield of the two tests is in same range or different, there is sufficient evidence to suggest the utility of EUS-FNA in nondiagnostic bronchoscopy and transbronchial needle aspiration (TBNA) (2, 3). Studies have shown that EUS-FNA has a sensitivity of 90 and 100% for the diagnosis of lung cancer after a nondiagnostic bronchoscopy and a negative TBNA, respectively (2, 3). In our study (1), the diagnostic yield of EUS-FNA varied from 57 to 100% depending upon the location of the tumor and presence of metastases. The diagnostic yield was high when the tumor was located near or adjacent to the esophagus (92%) and when there were metastases to mediastinal lymph nodes (79%) and distant sites (100%). Diagnostic yield was relatively lower (57%) when the tumor was peripherally located, and there was no CT evidence of metastases to the mediastinum. Pooled analysis (4) of studies that evaluated the diagnostic yield of bronchoscopy has also shown that the diagnostic yield of endobronchial biopsy is dependent on location and is in the same range as shown in our study: 74% for central disease and 46% for peripheral disease. Overall sensitivity for all bronchoscopic modalities combined was 88% and 69% for centrally and peripherally located lesions, respectively (4). We agree with Dr. Seijo that TBNA is underused by the practicing pulmonologist (5). The main reasons for this are that the test is performed "blindly," leading to low diagnostic yield and increased risk of complications. Addition of endobronchial ultrasound (EBUS) to TBNA increases the diagnostic yield, since it allows real-time controlled tissue sampling. Herth and coworkers showed that EBUS, EUS, and FNA have similar a diagnostic yield when mediastinal lymph nodes are enlarged (6). We also agree with the comments by Drs. Singh and Khan and have clarified those as a limitation in our study. We suggested EUS-FNA as a first diagnostic test (particularly for central lesions) based on its safety, high diagnostic yield, and accuracy for the detection of metastases. Ability of EUS-FNA to detect occult metastases to distant sites, particularly lymph nodes at the celiac axis, is an additional advantage over other diagnostic modalities since it avoids major thoracic surgery and lowers the overall cost of care. Prospective comparative studies of the transesophageal and transbronchial approach are required to determine the diagnostic yield in different clinical settings. Stage of lung malignancy (early versus advanced), location of the tumor (peripheral versus central), and availability of expertise with the various techniques would play a crucial role in deciding the initial diagnostic tests in suspected lung cancer.
Central Texas Veterans Health Care System, Temple, Texas
Scott & White Memorial Hospital, Temple, Texas FOOTNOTES Conflict of Interest Statement: Neither author has a financial relationship with a commercial entity that has an interest in the subject of this manuscript. REFERENCES
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