A Phase I/II Study of Hypofractionated Proton Therapy for Stage II-III Non-Small Cell Lung Cancer

Inclusion Criteria: * Pathologically confirmed invasive non-small cell lung cancer within 12 weeks prior to study registration. OR Pathologically confirmed invasive non-small cell lung cancer within 6 months prior to study registration if the patient received induction chemotherapy. * AJCC (American Joint Committee on Cancer) 7th Ed. clinical stage II-III. * ECOG Performance status 0-1 within 8 weeks prior to study registration. * Patient must give study-specific informed consent on an IRB-approved consent prior to any research-related procedures or study treatment. * Patient must be at least 18 years old at the time of consent. * Patient must complete all required tests in section 4. * Lab results per the following within 4 weeks prior to study registration: * Absolute neutrophil count (ANC) \>1,800 cells/mm3. * Platelets \> = 100,000 cells/mm3. * Hemoglobin \> =10 g/dl. The use of transfusion or other intervention to achieve Hgb ≥10.0 g/dl is acceptable. * AST/SGOT and ALT/SGPT \< 2.5 x the institutional upper limit of normal (IULN). * Post exploratory thoracotomy must be done \> 3 weeks prior to study registration or patient did not have post exploratory thoracotomy. * PFT (pulmonary function test) with a FEV1 \> 0.75 liters/second within 16 weeks prior to study registration. * Patients must be evaluated by a thoracic surgeon, pulmonologist or medical oncologist and deemed medically or surgically unacceptable for resection. Exclusion Criteria: * Evidence of distant metastasis (M1) involvement. * Prior radiotherapy to thoracic area. * Unintentional weight loss \>10% within 4 weeks prior to study registration. * Pregnant and/or breast-feeding women, or patients (men and women) of child-producing potential not willing to use medically acceptable forms of contraception while on study treatment and for at least 12 months after study treatment. Pregnancy testing is not necessary for women who have had a hysterectomy or have not had a menstrual period for at least 24 consecutive months.