This study aims to investigate a diagnostic yield and performance characteristics according to the order of endobronchial ultrasound guided transbronchial needle aspiration (EBUS-TBNA) and endoscopic ultrasound-with bronchoscope-guided transbronchial needle aspiration (EUS-B-FNA) in the mediastinal staging of potentially operable lung cancer. EUS-FNA is a better tolerated procedure than EBUS-TBNA. Therefore, EUS-B-FNA can be the main procedure in a combined approach with EBUS-TBNA and EUS-B-FNA. In group A, the investigators perform EBUS-TBNA first and EUS-B-FNA is performed when necessary. In group B, EUS-B-FNA is first applied and EBUS-TBNA is performed when necessary. The hypothesis is that the diagnostic yield of the EUS centered procedure is as good as that of the EBUS centered procedure and the EUS centered procedure is more tolerable than the EBUS centered procedure. We evaluate diagnostic yields and performance characteristics of each group.

Inclusion Criteria:

• Histologically confirmed or strongly suspected non-small cell lung cancer (NSCLC)
• Potentially operable patients

Exclusion Criteria:

• M1 disease
• Inoperable T4 disease
• Mediastinal infiltration or extranodal invasion of the mediastinal lymph node visible on chest CT.
• Confirmed supraclavicular lymph node metastasis
• Pancoast tumors
• Medically inoperable patients
• Contraindications for bronchoscopy and esophageal endoscopy
• Drug reaction to lidocaine, midazolam,fentanyl
• Pregnancy
• Ground glass-dominant nodule ( < 3cm)