Daily vs. Non-Daily SBRT for NSCLC

Inclusion Criteria: * ≥ 18 years of age (no upper age limit). * A diagnosis of non-small cell lung cancer, T1-2 N0 M0 either with histologic confirmation or with documented interval growth of the index lesion on two interval computed tomography (CT) chest scans and an SUVmax of the lesion ≥ 3.0 on a pretreatment PET scan. * Patient must be deemed medically inoperable or refuse surgery. * Radiographic evaluation of the mediastinum and distant sites with a CT scan of the chest and PET scan. * For T2b N0 patients, radiographic evaluation of the brain with magnetic resonance imaging (MRI) of the brain unless the patient has contraindications to an MRI scan (in which case a CT scan of the head is necessary). * For central T1 N0 and all T2 N0 patients, pathologic sampling (either via endobronchial ultrasound-guided biopsy \[EBUS\] or mediastinoscopy) of mediastinal lymph nodes is required. * ECOG Performance Status 0-2. * For women of childbearing potential, negative pregnancy test within 2 weeks prior to SBRT treatment. * Patients must be deemed able to comply with the treatment plan and follow-up schedule. * Patients must provide specific informed consent prior to study entry. * Women of childbearing potential and male participants who are sexually active must use adequate contraception during treatment and for 6 weeks following treatment. Exclusion Criteria: * Prior history of radiation therapy to the thorax that would likely increase the risk of serious complications from the radiotherapy delivered on this protocol. * Prior history of lung cancer. * Currently taking disease-modifying rheumatoid drugs (DMRDs). * Severe, active co-morbidity, defined as follows: * Acute bacterial or fungal infection requiring intravenous antibiotics at the time of registration. * Hepatic insufficiency resulting in clinical jaundice and/or coagulation defects. Note, however, that coagulation parameters are not required for entry into this protocol. * Prior organ transplant. * Systemic lupus. * Psoriatic arthritis. * Known to be HIV positive. HIV-positive patients are known to have worse clinical outcomes, especially for local, regional, and distant cancer control. This poorer prognosis is thought to be secondary to a compromised immune system.