DOI: 10.1097/MCG.0b013e3180684278
,
,
PMID: 17667046
Issn Print: 0192-0790
Publication Date: 2007/08/01
Transesophageal EUS and EUS-FNA for Lung Cancer: Where do we go From Here?
Excerpt
Endoscopic ultrasonography (EUS) incorporates a high-frequency ultrasound transducer into the tip of an endoscope to provide high-resolution images of the gastrointestinal (GI) wall and structures in close proximity to the GI tract above and below the diaphragm. Transesophageal EUS imaging provides high-resolution images of the posterior mediastinum and multiple studies have considered the utility of EUS for detection/staging of mediastinal lymphadenopathy in lung cancer. Before the development of interventional EUS techniques allowing EUS-guided fine-needle aspiration (FNA), the focus was on studying echo features of lymph nodes to predict malignant invasion. Lymph nodes that were larger than 1 cm, round, hypoechoic, and with distinct margins were considered to be malignant.1 These EUS defined criteria that were initially described for GI cancers (eg, esophageal) were later applied to mediastinal lymph nodes in lung cancer. EUS echo features of mediastinal lymph nodes in lung cancer were shown in one study to have accuracy of 84% compared with computerized tomographic (CT) scan accuracy of 49%.2 However, the reliance on EUS echo features to diagnose malignant lymph node invasion in lung cancer has problems of interobserver variability, lack of standardization of frequencies used to study the lymph nodes, and lack of uniform criteria to label a lymph node as hypoechoic or with sharp, distinct margins.3 In addition, it has been shown in a study by Bhutani et al3 that although the presence of echo features described above could predict malignant invasion about 80% of the time, only 25% of nodes that had malignant invasion had all 4 echo features. This study also compared the accuracy of echo features of lymph nodes in patients with esophageal, pancreatic, and lung cancer to EUS-guided FNA. The authors found that EUS-guided FNA was a more reliable method for predicting lymph node invasion than echo features. Transesophageal EUS-guided real-time FNA of mediastinal lymph nodes has become a clinically useful minimally invasive method for detecting malignant lymph node invasion.3–7 EUS-FNA is well suited for evaluation of the mediastinum with lymph nodes in the subcarina, aorto-pulmonary window, para-esophageal area, and para-aortic area being the most amenable locations for EUS-guided FNA. One study is reporting 96% accuracy of EUS-FNA in patients with known nonsmall cell lung cancer who have enlarged mediastinal lymph nodes on CT scan.2 When a primary lung mass is seen on CT with enlarged mediastinal lymph nodes in the mediastinum, EUS-guided mediastinal FNA can provide a primary diagnosis and simultaneous staging information.6,7 Recent data suggest that EUS-guided FNA may detect advanced mediastinal disease and avoid un-necessary surgical exploration in a significant number of patients who have no evidence of enlarged mediastinal lymph nodes on CT scan.8–10 In a series of 104 patients the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of EUS-FNA were 92.5%, 100%, 100%, 94%, and 97%, respectively. EUS-FNA was more accurate and had a higher positive predictive value than the positron emission tomography (PET) or CT (P<0.001) scan in confirming cancer in the posterior mediastinal lymph nodes.11 EUS with FNA has also been found in some studies to be useful in sampling the left adrenal gland in nonsmall cell lung cancer.12,13 A few cost effectiveness and decision modeling studies have also been published showing EUS-FNA to be cost effective in staging nonsmall cell lung cancer.14–17 EUS is also useful in evaluating mediastinal lymphadenopathy of unknown origin with no primary lung mass on CT.
Facebook
Twitter
LinkedIn
Email
