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.