PET-Adjusted Intensity Modulated Radiation Therapy and Combination Chemotherapy in Treating Patients With Stage II-IV Non-small Cell Lung Cancer

Inclusion Criteria: * Pathologically proven (either histologic or cytologic) diagnosis of NSCLC with any of the following stages (according to the American Joint Committee on Cancer \[AJCC\] Staging Manual, 7th edition): * Stage IIIA or IIIB * Stage II NSCLC with medical contraindication to curative surgical resection * Stage IV disease with solitary brain metastasis that has been treated radically (eg: with surgical resection or stereotactic radiosurgery) and thoracic disease that would be classified as stage II-III * Appropriate diagnostic/staging workup, including: * Complete history and physical examination * Whole body PET/computed tomography (CT) scan within 42 days prior to study entry demonstrating hypermetabolic pulmonary lesion(s) and/or thoracic lymph node(s), with a maximum standardized uptake volume (SUV) \> 6 for at least one lesion; if PET/CT was obtained more than 42 days prior to study entry and is not repeated, CT scan of the chest within 28 days prior to study entry demonstrating stable disease is required * Magnetic resonance imaging (MRI) of the brain or CT scan of the head with contrast within 42 days prior to study entry * Biopsy confirmation of suspected metastatic disease identified by PET/CT is recommended * Pulmonary function tests (PFTs) within 6 weeks of study entry are highly recommended but not required * No prior chemotherapy or thoracic radiotherapy for lung cancer * Eastern Cooperative Oncology Group (ECOG) performance stat…