11. For patients with left-sided tumors and enlarged nodes (>1.0 cm in the shortest diameter) on the aortopulmonary window setting, the aortopulmonary nodes must be biopsied by extended mediastinoscopy, Chamberlain procedure, video-assisted thoracoscopic surgery (VATS) approach, or ultrasound-guided biopsy to ensure that the patient does not have N2 disease. At the time of cervical mediastinoscopy, esophageal endoscopic ultrasound-guided biopsy, or endobronchial ultrasound-guided biopsy, the following nodal stations must be examined and biopsied, if present: *ipsilateral nodal station 4 *contralateral nodal station level 4, and *subcarinal nodes (level 7). For left-sided tumors, any lymph node in the superior or anterior mediastinum >1.0 cm in the shortest axis on CT or positive on PET must be identified and biopsied. Eligibility requires that any PET-positive mediastinal or distant sites must be biopsy-negative.