Gated Intensity Modulated Radiation Therapy and Concurrent Chemotherapy for Inoperable NSCLC

Inclusion Criteria: * Patients with histologically-proven, by biopsy or cytology, unresectable lung cancer of the following histologic types: squamous cell carcinoma, adenocarcinoma, large cell carcinoma, non-small cell carcinoma, not otherwise specified. * Patient with AJCC Stage IIIA-IIIB, if all detectable tumor can be encompassed by radiation therapy fields, including both the primary tumor and the involved regional lymph nodes. * 18-fluoro-2-deoxyglucose positron emission tomography required for staging and image fusion for treatment planning. * Atelectasis, if present, must be less than one lung. * Patients must have granulocytes \>1500/µl; platelets \>100,000/µl; bilirubin \< 1.5 mg/dl; AST(SGOT) \< 2 ULN; serum creatinine \< 2.0 mg/dl. * Zubrod Score 0-1. * FEV1 must be \>1.0 L. * Patients must sign a study-specific informed consent form prior to study entry * Patients must have measurable disease on the planning CT. * Patient must have a completed the IMRT plan and the attending physician must have reviewed and approved the dose volume histograms as follows (based on treatment planning to the Phase 4 dose level): total lung V20 \< 30%, mean esophageal dose \< 34 Gy, the esophageal V55 \< 30%, the heart V40 \< 50%. * No prior or concurrent malignancy except non-melanomatous skin cancer unless disease-free for one year or more; no prior lung cancer within last two years. * No prior RT to thorax. * No previous chemotherapy or previous biologic response modifiers for current lung cancer or within the past five (5) years. * No distant metastases or supraclavicular lymph node involvement or significant atelectasis. * No clinically significant pleural effusions, pericardial effusions or superior vena cava syndrome. Exclusion Criteria: * Undifferentiated small cell (oat cell or high grade neuroendocrine) carcinoma, any stage. * Stage I, II or IV NSCLC. * Complete tumor resection, recurrent disease, or those patients eligible for definitive surgery. * Concurrent malignancy except non-melanomatous skin cancer or prior cancer unless disease-free for one year or more. * Prior radiation therapy to the thorax. * Previous chemotherapy or previous biologic response modifiers for current lung cancer or within the past five (5) years. * Distant metastases or supraclavicular lymph node involvement, or atelectasis of an entire lung. * Patients who have not had the pre-treatment evaluations in Section 4.0 or evaluations performed \> 8 weeks prior to study entry. * Patients with clinically significant pleural effusions, pericardial effusions or superior vena cava syndrome. * Prior lung cancer within the last two years. * Patients who have significant atelectasis and in whom the CT definition of the gross tumor volume(GTV) is difficult to determine. * Pregnant or lactating females. It is not known what effects this treatment may have on the developing fetus.