Inclusion Criteria:

• Histological confirmation of non-small cell lung cancer
• Forced Expiratory volume in 1 second (FEV1)>1.0 L
• Unresectable stage 2-3 Non-small cell lung cancer (based on CT/positron emission tomography (PET), MRI or CT of brain, and physical exam). 
  • Eligible if recurrence after surgery and now has the equivalent stage 2-3 NSCLC OR had sub totally resected stage 2-3 NSCLC.
• Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) 0-1
• Negative pregnancy test done ≤7 days prior to registration, for women of childbearing potential only.
• The following laboratory values in specified ranges:
  • White blood cell count (WBC) ≥3.0 x 109/L,
  • Absolute neutrophil count (ANC) ≥1.5 x 109/L,
  • Hgb ≥9g/dl
  • Plts >100 x 109/L
  • Serum creatinine<1.5 times upper limit of normal (ULN)
  • Serum bilirubin <1.5 times upper limit of normal (ULN)
• Provide informed written consent.
• Willing to return to enrolling institution for follow-up for a minimum of 1 year.
• Ability to undergo potentially curative chemotherapy plus radiotherapy

Exclusion Criteria:

• Any of the following because this study involves an agent that has known genotoxic, mutagenic and teratogenic effects:
  • Pregnant women;
  • Nursing women;
  • Men or women of childbearing potential who are unwilling to employ adequate contraception.
• Co-morbid systemic illnesses or other severe concurrent disease which, in the judgment of the investigator, would make the patient inappropriate for entry into this study or interfere significantly with the proper assessment of safety and toxicity of the prescribed regimens.
• Weight loss of >10% in the past 3 months
• Distant metastases (M1 disease)
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, lupus, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements.
• Receiving any investigational agent, that would be considered as a treatment for the primary neoplasm.
• Active second malignancy.
• Other active malignancy ≤3 years prior to registration. EXCEPTIONS:
  • Treated non-melanotic skin cancer;
  • Carcinoma-in-situ of the cervix;
  • Treated Stage 1-2;
  • Gleason 7 or less;
  • Prostate cancer with a stable or undetectable prostate specific antigen (PSA) level;
  • Treated stage 1 breast cancer which is controlled and for which the patient received no thoracic radiotherapy (RT).
• History of myocardial infarction ≤6 months, or congestive heart failure requiring use of ongoing maintenance therapy for life-threatening ventricular arrhythmias.
• Received chemotherapy for lung cancer within 6 months of registration.
• Previous chest radiotherapy that would overlap with the proton field.