© 2007 American Thoracic Society doi: 10.1164/rccm.200609-1390ED
Esophageal Endoscopic Ultrasound/Endobronchial Ultrasound–guided Fine Needle AspirationA New Dawn for the Respiratory Physician?Centre for Respiratory Research, University College London, London, United Kingdom
University College London Hospital, London, United Kingdom The rapid diagnosis and accurate staging of patients suspected of having lung cancer is recognized as best care, and should be achieved with as few procedures as possible. Most centers now perform thoracic and upper abdominal computed tomography (CT) first to assess whether fiberoptic bronchoscopy (FOB), transthoracic CT, ultrasound (US)–guided fine needle aspiration, or sampling of a distant lymph node or organ suspected to contain metastatic tissue is the procedure of choice. Establishing the diagnosis and the presence of metastatic spread at a single test has the most profound effect on management, and is clearly desirable. Until relatively recently, mediastinal node sampling depended on cervical mediastinoscopy, which has the limitation of only accessing the left and right paratracheal, carinal, and subcarinal nodes, leaving nodes in the aortopulmonary window and preaortic and subaortic nodes to be explored by an anterior mediastinotomy. The posterior and inferior nodes are largely not accessible to either technique. The advent of US-guided endoscopes, through which fine needle aspiration is possible, is changing the diagnostic algorithm. Endobronchial US–guided fine needle aspiration (EBUS) can be performed during FOB, and a prior CT allows nodes to be targeted and sampled, mainly in the same areas accessible to cervical mediastinoscopy, with the addition of some hilar nodes. Esophageal endoscopic ultrasound (EUS) allows examination of the posterior and inferior mediastinum and far more—the liver, the celiac axis, and the left adrenal gland. A report in this issue of the Journal (pp. 345–354) by Singh and colleagues highlights the diagnostic yield and possibilities of EUS (1). Singh and colleagues took 157 consecutive cases suspected of lung cancer. They all underwent CT and EUS and 106 had a positron emission tomography (PET) scan. Of these cases, 113 were diagnosed with lung cancer and, importantly, the authors did not include direct sampling of the primary tumor in their diagnostic approach. They focused only on possible metastatic disease. By performing EUS as the first test after CT, Singh and colleagues made the diagnosis in 82% of cases, and EUS fine needle aspiration established a tissue diagnosis in 70%. This was more accurate at diagnosing metastases in the mediastinum than CT and PET. EUS fine needle aspiration was also superior to CT at diagnosing extrathoracic disease, particularly in the liver, the celiac axis, and left adrenal gland. In all, 14% of patients avoided a futile thoracotomy. Other studies of patients with lung cancer requiring mediastinal evaluation have also found that EUS was more sensitive and specific than CT and PET (2–6). Indeed, it may also be more accurate than mediastinoscopy (7), and one study showed that 37% of patients with negative mediastinoscopy had metastatic nodes on EUS (8). The study by Singh and colleagues, although not the first of its kind, raises several important issues for respiratory physicians. Traditional staging has tended to focus on defining the disease stage of the mediastinum as the predictor of resectability. Although this may vary a little between cell types, it is still broadly true that almost all patients with extrathoracic metastases will have metastatic mediastinal nodes (9). Clearly, US-guided techniques should render mediastinoscopy redundant in most cases. Mediastinoscopy is time consuming and expensive, causes delay with surgical transfer, has morbidity, and its sensitivity has been reported to be as low as 81% (10). Furthermore, Singh and coworkers show EUS to be less dependent on identifying metastases by lymph node size, which is the cornerstone of CT. In skilled hands, EUS offers a genuine advance in the potential for diagnosis and staging, but perhaps it should be seen as complementary to EBUS. A comparison of EUS with EBUS found each approach had a similar diagnostic yield, with EBUS better for right-sided nodes (11). The highest yield for diagnosis and staging lung cancer will depend on the ability to perform whichever test is best out of EBUS, EUS, or CT fine needle aspiration at a single session. It is noteworthy that none of the authors of Singh and colleagues' study is a respiratory physician. The EUS was performed by a gastroenterologist. Is this really a necessity? After all, respiratory physicians gently but firmly took rigid bronchoscopy from the surgeons with the development of flexible fibroscopes in the late 1960s. Why shouldn't dedicated cancer centers have a trained, experienced respiratory physician capable of performing both US techniques as necessary, thus allowing much more potential from a single procedure? In many hospitals, the endoscopy suites are under great pressure for space as technology expands its role. This makes combining EBUS and EUS attractive, although patients may have to be transferred to a cancer center for this. Indeed the up-front costs of US-guided endoscopes approach $150,000 in the United Kingdom, which will make their widespread availability unlikely in the near future. However, the potential for savings is huge in reducing the numbers of procedures, avoiding mediastinoscopy, and faster staging (8). The role of the respiratory physician today in lung cancer is mainly in diagnosis, staging, breaking the news, and referring to a surgeon or oncologist. EUS (and EBUS) will become essential parts of the investigative algorithm of lung cancer, so respiratory physicians who routinely perform FOB should not be put off from learning their way around the upper gastrointestinal tract when we so casually navigate the complexities of the bronchial tree. There is a steep learning curve to these generally safe techniques and expert training is mandatory, but the time to start is now. Or at least to have the debate. 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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