A defining hallmark of cancer is its capability to metastasize. With few exceptions, patients with metastatic disease are considered incurable, and when offered treatment, the intent is to palliate symptoms and delay the inevitable morbidity and mortality that accompanies disease progression. Systemic therapy has been and remains the mainstay of treatment for metastatic disease, however the decision to initiate or continue systemic therapy is a balance of the anticipated benefits and the adverse effects of treatment. Virtually all patients eventually reach a point where systemic therapy will be ceased.~Therapeutic radiotherapy in cancer care can be prescribed with curative or palliative intent. Palliative radiotherapy has long held a role in improving or stabilizing symptoms such as pain, bleeding, or neurologic dysfunction by delivering relatively low radiation doses to metastatic tumours. While palliating symptoms continues to be an important indication, the use of high dose, conformal radiotherapy, termed stereotactic ablative radiotherapy (SABR), has gained traction as an alternative treatment option for select metastatic patients, primarily those with oligometastatic disease.~The objective of this trial is to determine the impact of SABR on overall survival, progression-free survival, quality of life, and toxicity in patients with polymetastatic disease.
This is a phase II/III international multicentre randomized trial. Patients will be randomized in a 1:2 ratio between the standard of care (Arm 1) and SABR (Arm 2) to all sites of disease. The study will start as a phase II trial with an opportunity to convert to a phase III trial. The objective of this trial is to determine the impact of SABR on overall survival, progression-free survival, quality of life, and toxicity in patients with polymetastatic disease.