The Role of Stereo-tActic BoDy RadIotherApy iN Oligo-Progressive MalignanT Disease

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