Zapping just a few spots: new hope for patients with worsening metastatic cancer?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Adult patients ≥18 years accrued at the Princess Margaret Cancer Centre * 5 or less sites of intra or extra-cranial oligo-progressive, de novo oligo-metastatic, induced oligo-metastatic and repeat oligo-metastatic breast disease amenable to ablative treatment (including but not limited to radiotherapy, surgery, radio-frequency ablation); o at least one lesion should be planned for SBRT * OR 5 or less sites of intra or extra-cranial oligo-progressive prostate, bladder and renal cell carcinomas * Tumor mass amenable to SABR (≤6cm in size) * Confirmation of diagnosis: * Known/documented prior histological (for all excluding HCC) or radiological diagnosis (for HCC) of: * Pathologically confirmed breast cancer OR, * Pathologically confirmed GU cancer (such as prostate cancer, bladder cancer, or radiologically or pathologically confirmed RCC). * For prostate patients only: Known metastatic disease treated with ADT (patients who received other ST as first line treatment of mCSPC would be eligible; eg Docetaxel, Abiraterone…) * For prostate patients only: Known metastatic CRPC progressing on ST (Docetaxel, Abiraterone, Enzalutamide…) * For oligo-progressive disease: receiving any form of ST for at least 3 months with (ST breaks are permitted): 1. Radiographic evidence of ≤3 intra or extra-cranial lesions progressing (including nodal or distant). At least one lesion is suitable for SBRT. Each progressing lesion should fulfill at least 1 of the 3 following criteria for oligo-progression: 1. Progression of a metastasis according to RECIST 1.1 criteria7 2. Unambiguous development of a new lesion from the time of scan taken prior to starting ST 3. Progressive enlargement of a known metastasis on 2 consecutive imaging (CT or MRI) 2-3 months apart, while on ST, with a minimum 5 mm increase in size from baseline. 2. Remainder of metastatic disease stable or regressing, as per RECIST v1.1, evidenced by \>2 consecutive images within the past 4-6 months. * Able to provide written consent * ECOG performance status 0-3 Exclusion Criteria: * ≥6 progressive metastases * Evidence of spinal cord compression or acute event requiring urgent/emergency radiotherapy * Prior radiotherapy, with fields overlapping, resulting in excessive doses to organs at risk * Previous radical RT in the area of OP * Inability to safely treat all sites of progressing metastases * Patient cannot tolerate physical set-up required for SBRT * Treatment plan respecting normal tissue tolerances using dose fractionation specified within the protocol cannot be achieved * Active bowel obstruction, if treating abdominal/pelvic site * Neuroendocrine, lymphoma, myeloma or germ cell malignancies * Familial syndromes: Von Hippel-Lindau disease, Polycystic Kidney Disease, Hereditary Papillary RCC or Tuberous Sclerosis