Accuracy of EUS criteria and primary tumor site for identification of mediastinal lymph node metastasis from non-small-cell lung cancer

Background: EUS with FNA is useful for staging non-small-cell lung cancer. However, benign mediastinal adenopathy is common. The aims of this study were to identify clinical factors, especially primary tumor location, and EUS lymph nodal characteristics predictive of aortopulmonary window and subcarinal lymph node metastases of non-small-cell lung cancer. Methods: Patients with known or suspected non-small-cell lung cancer underwent EUS staging at which EUS-FNA was performed for all identified mediastinal lymph nodes. Clinical characteristics, primary tumor data, EUS findings, and histopathology were reviewed. Exact tests were performed for both aortopulmonary window and subcarinal lymph nodes to identify factors predictive of malignant cytology. Results: Ninety-two patients with non-small-cell lung cancer were included. Fifty-one had aortopulmonary window, and 73 had subcarinal lymph nodes on EUS. The EUS with FNA specimens were interpreted as suspicious or diagnostic for malignancy for 9 aortopulmonary window and 9 subcarinal lymph nodes. When comparing benign vs. malignant EUS with FNA findings for aortopulmonary window and subcarinal lymph nodes, only lymph node size of 1 cm or greater and sharp lymph nodal edges were associated with malignancy in lymph nodes at both sites, whereas primary tumor site, lymph node shape, and echogenicity were associated with malignant subcarinal nodes. When 4 classic lymph nodal features of malignancy were evaluated, the presence of 3 or more typical features had positive and negative predictive values of, respectively, 41% and 96%. Conclusions: Although tumor location and EUS lymph nodal characteristics are associated with malignant involvement of lymph nodes, the accuracy of these predictors does not obviate the need for cytologic evaluation. EUS with FNA should be performed for all lymph nodes when an abnormal finding will alter management.