Inclusion Criteria:

          -  Metastatic disease detected on imaging and histologically confirmed

               -  Triple negative breast cancer (TNBC) (ER <1%, PR <1%, her-2-neu 0-1+ by IHC or
                  FISH-negative or as determined by MD discretion),

               -  ER+ breast cancer receiving chemotherapy regardless of HER2 status

               -  Non-small cell lung cancer (NSCLC) without known targetable molecular alterations
                  in EGFR, ALK, or ROS1

               -  NSCLC with EGFR, ALK, or ROS1 targetable molecular alterations who had a history
                  of disease progression on first-line tyrosine kinase inhibitor

          -  Patient can either have newly diagnosed metastatic disease, or have non-progressive
             disease on systemic therapy (for at least 3 months on systemic imaging)

          -  Patients must have measurable disease at baseline (RECIST or PERCIST 2.0) and with 5
             or fewer discrete disease sites that are technically amendable to SBRT (with the
             exception that if the primary disease is not amendable to SBRT it is allowed to be
             treated with conventionally fractionated or hypfractionated radiotherapy).

               -  Two lesions in such close proximity to one another that treatment with one
                  isocenter is more accurate and safer in the liver, lungs, or other similar
                  anatomic locations should be viewed as one site of metastatic disease treatment

               -  Disease in 2 contiguous vertebral bodies (with up to 6 cm of paraspinal
                  extension) can represent one site of disease in the spine; non-contiguous lesions
                  in vertebral bodies separated by one vertebral body free of disease should be
                  viewed as 2 sites of treatment

               -  If the clinical scenario deem that other forms of local therapy may be more
                  suitable for the metastatic disease, such as surgical resection and
                  interventional radiology-guided ablation, patients would be able to undergo other
                  forms of local therapy with discussion with the PI.

          -  For de novo stage IV patients (patients with metastatic disease at first
             presentation), primary disease must be treatable with local therapy. If the primary
             tumor or other locoregional disease has not been definitively treated and is not
             amendable to SBRT, it must be treated with conventionally fractionated or
             hypofractionated radiotherapy using a regimen that delivers a minimum BED of 48 Gy10.
             If the clinical scenario deem that other forms of local therapy may be more suitable
             for the primary and locoregional disease, such as surgical resection and
             interventional radiology-guided ablation, patients would be able to undergo other
             forms of local therapy with discussion with the PI.

          -  If primary disease was previously treated with local therapy in the form of surgery or
             radiation, any new local/regional disease recurrence should be technically treatable
             with SBRT or hypofractionated radiation. If the clinical scenario deem that other
             forms of local therapy may be more suitable for the local/regional recurrent disease,
             such as surgical resection and interventional radiology-guided ablation, patients
             would be able to undergo other forms of local therapy with discussion with the PI.

          -  Patients may receive palliative radiotherapy for symptomatic metastases or primary
             disease prior to enrollment provided that there is at least one other non-irradiated
             lesion amenable to SBRT at the time of enrollment.

          -  Patients with brain metastases are eligible if these lesions have been treated prior
             to enrollment.

          -  ECOG Performance status 0 - 2.

          -  Age >/= 18 years.

          -  Able to provide informed consent.

          -  Female subjects must either be of non-reproductive potential (i.e. post-menopausal by
             history: >/= 60 years old or no menses for 1> year without an alternative medical
             cause; OR history of hysterectomy, OR history of bilateral tubal ligation, OR history
             of bilateral oophorectomy) or must have a negative serum pregnancy test within 2 weeks
             prior to starting treatment.

          -  Adequate baseline organ function to allow SBRT to all relevant targets, as determined
             by the treating radiation oncologist based on lesion location, lesion size, and
             proximity to relevant organs at risk.

        Exclusion Criteria:

          -  Serious medical co-morbidities precluding radiotherapy, determined at the discretion
             of the treating investigator.

          -  Pregnant or lactating women.

          -  Other active malignancy within the last year, even if without evidence of disease.

          -  Clinical or radiological evidence of spinal cord compression

          -  Malignant pleural effusion or ascites.

          -  Patients whose entry to the trial will cause unacceptable clinical delays in their
             planned management.