Usefulness of Transesophageal Bronchoscopic Ultrasound-guided Fine-Needle Aspiration in the Pathologic and Molecular Diagnosis of Lung Cancer Lesions Adjacent to the Esophagus

Background: The discovery of driver oncogenes has increased the need to obtain a sufficient amount of tissue specimens for lung cancer diagnosis. Although endoscopic ultrasound (with bronchoscope)-guided fine-needle aspiration (EUS-B-FNA) is reportedly a feasible and well-tolerated modality, additional advantages of EUS-B-FNA are yet to be thoroughly investigated. The purpose of this study was to evaluate the ability of EUS-B-FNA to obtain sufficient tissue specimens for pathologic and molecular diagnoses of lung cancer. Methods: Among lung cancer patients who were diagnosed between December 2010 and December 2012 in our institute, patients who underwent EUS-B-FNA to diagnose lung cancer were enrolled (n=26). EUS-BFNA was performed when bronchoscopic diagnosis was impossible or difficult to obtain sufficient samples. Epidermal growth factor receptor (EGFR) mutations and echinoderm microtubule-associated protein-like 4 and the anaplastic lymphoma kinase (EML4-ALK) fusion gene were evaluated using EUS-B-FNA samples of non-small cell lung cancer. Results: EUS-B-FNA was performed on 28 lesions in 26 patients. Among the target lesions, 23 were mediastinal lymph nodes including nodal stations 2L, 4L, 7, 8, and 10L. The remaining 5 were intrapulmonary lesions. EUS-B-FNAs were completed without complications in all the patients. The diagnostic yield of EUS-B-FNA in diagnosing lung cancer was 100% (26/26). Additional diagnostic gain of EUS-B-FNA was 69.2% (18/26) as compared to bronchoscopy alone. EGFR mutations and EML4-ALK fusion gene could be evaluated in all patients with non-small cell lung cancer (n=20) using EUS-B-FNA samples. One case with EGFR mutation and 1 case with ALK fusion gene were diagnosed. Six non-small cell carcinomas were also diagnosed by bronchoscopy, but all bronchoscopic samples were insufficient to evaluate mutation analyses. Conclusions: EUS-B-FNA is a practical and feasible method to obtain abundant tumorous tissue samples for pathologic diagnosis and molecular analysis, particularly when the target lesions are inaccessible by other modalities because of their locations or because of the patient's poor physical condition.