10. The following mandatory staging studies must be done within 12 weeks before study registration: *PET/CT scans of both lungs, the mediastinum, adrenal glands and rest of the body; primary tumor dimension will be measured on diagnostic CT and again on simulation CT using the lung window setting. *Mediastinoscopy or endobronchial ultrasound -guided biopsy of the mediastinal lymph nodes is recommended and required for any patients with PET/CT or CT findings suggesting lymph node involvement. *Brain MRI or CT scan if symptoms or signs suggest brain metastases. *Invasive mediastinal staging: For all patients with CT or PET evidence of hilar involvement (level 10) or with mediastinal lymph nodes >1.0 cm in the shortest diameter or clinically suspicious by treating physician and/or radiologist, disease must be staged by cervical mediastinoscopy, esophageal endoscopic ultrasound-guided biopsy, or endobronchial ultrasound-guided biopsy.