Inclusion Criteria:

- Age 18 or older

- Willing to provide informed consent

- Histologically confirmed malignancy with metastatic disease detected on imaging.
Biopsy of metastasis is preferred, but not required.

- ECOG performance status 0-1

- Controlled primary tumor

a. defined as: at least 3 months since original tumor treated definitively, with no
progression at primary site

- All sites of disease can be safely treated based on criteria below

- Maximum 3 metastases in any single organ system (i.e. lung, liver, brain, bone)

- Life expectancy >6 months

- Not a candidate for surgical resection at all sites: surgery to all sites not
recommended by multidisciplinary team, or unfit or declining surgery

- Prior chemotherapy allowed but no systemic therapy 4 weeks prior to first fraction of
radiotherapy, during radiotherapy, or for two weeks after last fraction

- Patients with metastases that have been previously treated (e.g. prior resection,
Radiofrequency Ablation (RFA) or radiotherapy):

a. If that previously treated metastasis is controlled on imaging, the patient is
eligible for this study and that site does not need treatment

a. If that previously treated metastasis is NOT controlled on imaging:

1. If the previous treatment was surgery, the patient is eligible if that site can
be treated by SABR

2. If the previous treatment was radiotherapy or RFA, the patient is ineligible.

- Patient presented at multidisciplinary tumor board or quality-assurance rounds.

Exclusion Criteria:

- Serious medical comorbidities precluding radiotherapy

- Bone metastasis in a femoral bone

- Patients with 1-3 brain metastasis and no disease elsewhere (these patients should
not be randomized but treated with stereotactic radiotherapy as per results of
randomized trials)

- Prior radiotherapy to a site requiring treatment

- Complete response to first-line chemotherapy (i.e. no measurable target for SABR)

- Malignant pleural effusion

- Inability to treat all sites of active disease

- Clinical or radiologic evidence of spinal cord compression OR tumor within 3 mm of
spinal cord on Magnetic Resonance Imaging (MRI).

- Dominant brain metastasis requiring surgical decompression

- Pregnant or lactating women