Inclusion Criteria:

• Patients must have the psychological ability and general health that permits completion of the study requirements and required follow up
• Women of childbearing potential and men who are sexually active should be willing and able to use medically acceptable forms of contraception during the trial
• Pathologically proven diagnosis of NSCLC, with metastases (stage IV disease) present prior to registration; this includes patients newly diagnosed with metastatic disease or those initially diagnosed and treated for stage I-III NSCLC who ultimately develop metastases
• Appropriate stage for study entry based on the following diagnostic workup:
  • History/physical examination within 30 days prior to registration
  • Imaging proof of limited metastatic disease and response to therapy/stable disease, by at least CT chest through the adrenals or PET/CT within 30 days prior to registration
• Zubrod performance status 0, 1, or 2 within 30 days prior to registration
• Aspartate transaminase (AST) and alanine transaminase (ALT) ≤ 2.5 × upper limit of normal (ULN) or ≤ 5 × ULN with metastatic liver disease
• Total bilirubin ≤ 1.5 × ULN
• Absolute neutrophil count (ANC) ≥ 500 cells/mm^3
• Creatinine clearance ≥ 45 mL/min/1.73 m^2 for patients with creatinine levels above institutional normal
• Platelets ≥ 50,000 cells/mm^3
• Negative serum pregnancy test within one week prior to registration for females of childbearing potential
• Patients must have received first-line/induction chemotherapy (4 cycles) and achieved stable disease or a partial response
• Prior systemic chemotherapy as part of concurrent treatment approach for previously diagnosed stage III NSCLC, as adjuvant therapy for previously resected NSCLC, or for other previous cancers is permitted
• Prior radiotherapy for patients with brain metastases prior to enrollment is acceptable
• Patients must have measurable disease at baseline and 3 or fewer discrete, extracranial metastatic disease sites that are technically amenable to SBRT
• For de novo stage IV NSCLC patients (patients with metastatic disease at first presentation), primary disease must be treatable with local therapy in the form of SBRT or hypofractionated radiation; if the primary disease is found in the peripheral or central lung parenchyma without nodal disease for instance, SBRT may be employed; if primary disease is more advanced with involvement of the mediastinum (T4 tumor, N1-N3 disease, etc.), these volumes should be technically treatable with hypofractionated radiation
• If primary disease in the thoracic cavity was previously treated with local therapy in the form of surgery, any local/regional disease recurrence should be technically treatable with SBRT or hypofractionated radiation after induction systemic therapy
• Patients must be registered within 35 days of administration of the last dose of first-line/induction systemic therapy
• The patient or a legally authorized representative must provide study-specific informed consent prior to study entry
• Patients with brain metastases are eligible if these lesions have been previously treated and the patients have no clinical or radiographic evidence of progression prior to enrollment

Exclusion Criteria:

• Clinical or radiologic evidence of untreated and/or progressive brain metastases
• Cutaneous metastasis of NSCLC
• Metastatic disease invading the esophagus, stomach, intestines, or mesenteric lymph nodes
• Prior invasive malignancy (except non-melanomatous skin cancer, low or intermediate risk prostate cancer, or in situ carcinoma of breast, oral cavity, skin, or cervix) unless disease free for a minimum of one year
• Metastases located within 3 cm of previously irradiated (< 3Gy per fraction) structures if:
  • Spinal cord previously irradiated to > 40 Gy
  • Brachial plexus previously irradiated to > 50 Gy
  • Small intestine, large intestine, or stomach previously irradiated to > 45 Gy
  • Brainstem previously irradiated to > 50 Gy
  • Lung previously irradiated with prior V20 Gy > 35%
• Patients receiving targeted therapy (non-cytotoxic systemic therapy) for NSCLC in the first-line setting
• If a patient has progressed in previous areas of primary disease that received definitive doses of radiation, these patients would require re-irradiation in previous high dose anatomic areas and are not eligible for this study
• Patients with malignant pleural effusions that do not resolve after first-line systemic therapy; patients with pleural effusions that have become too small for thoracentesis at the time of registration would be permitted on study, indicating a significant response to first-line chemotherapy
• Patients with more than 3 discrete locations of extra-cranial metastatic disease after first-line systemic therapy requiring more than 3 SBRT plans to cover these distinct metastatic disease entities
• Acute bacterial or fungal infection requiring intravenous antibiotics at the time of registration
• Patients who are pregnant or nursing
• Participation in any investigational drug study (excluding non-oncology and/or symptom management studies) within 4 weeks prior to registration
• Known human immunodeficiency virus (HIV) positive with cluster of differentiation 4 (CD4) count < 200 cells/microliter; note that patients who are HIV positive are eligible, provided they are under treatment with highly active antiretroviral therapy (HAART) and have a CD4 count ≥ 200 cells/microliter within 30 days prior to registration; note also that HIV testing is not required for eligibility for this protocol