Pathologically confirmed, by biopsy or cytology, non-small cell lung carcinoma diagnosed within 3 months prior to study enrollment.

T1, N0, M0 or T2, N0, M0. (AJCC Lung 7th Edition)

At least 18 years old at the time of consent.

Adequate bone marrow function.

Medically inoperable. Medically operable candidates are allowed if they refuse surgical resection.

If the patient has a large pleural effusion, it must be biopsy negative.

Proton Therapy for Stage I Non-Small Cell Lung Cancer (LU03)