Median progression free survival following SBRT to progression, starting new treatment or death from any cause.

Progression is defined as one of the following; (i) PSA progression: PSA rise by at least 25% over post-SBRT baseline (set at 4 weeks), confirmed by a second reading at least 4 weeks later, (ii) Radiological progression: at least 2 new lesions on bone scan or unequivocal progression of soft tissue on CT, or evidence on other local imaging of disease progression (e.g. PET or MRI progression) as per Response Evaluation Criteria In Solid Tumours Criteria (RECIST v1.1) (iii) Symptomatic progression: new or progressing symptoms at the site of a metastasis, or (iv) Date at which the clinician decides to stop Abiraterone/Enzalutamide or starts new line of therapy, whichever occurs sooner.

81 patients received SBRT and were evaluable for the primary endpoint.

Number of patients that had a PFS event following SBRT in the duration of the study. Progression free survival definition is time from SBRT to progression, starting new treatment or death from any cause.

Progression is defined as one of the following; (i) PSA progression: PSA rise by at least 25% over post-SBRT baseline (set at 4 weeks), confirmed by a second reading at least 4 weeks later, (ii) Radiological progression: at least 2 new lesions on bone scan or unequivocal progression of soft tissue on CT, or evidence on other local imaging of disease progression (e.g. PET or MRI progression) as per Response Evaluation Criteria In Solid Tumours Criteria (RECIST v1.1) (iii) Symptomatic progression: new or progressing symptoms at the site of a metastasis, or (iv) Date at which the clinician decides to stop Abiraterone/Enzalutamide or starts new line of therapy, whichever occurs sooner.

81 patients received SBRT treatment and were evaluable for this endpoint.

Progression free survival estimates following SBRT to progression, starting new treatment or death from any cause.

Progression is defined as one of the following; (i) PSA progression: PSA rise by at least 25% over post-SBRT baseline (set at 4 weeks), confirmed by a second reading at least 4 weeks later, (ii) Radiological progression: at least 2 new lesions on bone scan or unequivocal progression of soft tissue on CT, or evidence on other local imaging of disease progression (e.g. PET or MRI progression) as per Response Evaluation Criteria In Solid Tumours Criteria (RECIST v1.1) (iii) Symptomatic progression: new or progressing symptoms at the site of a metastasis, or (iv) Date at which the clinician decides to stop Abiraterone/Enzalutamide or starts new line of therapy, whichever occurs sooner.

81 patients received SBRT treatment and were evaluable for this endpoint.

Overall control defined as stable disease or partial response of irradiated metastases assessed using the RECIST (v 1.1) criteria on imaging such as computed Tomography (CT), magnetic Resonance Imaging (MRI) or Positron Emission Tomography (PET) scan or control on bone scan

Of the 81 patients who received SBRT treatment, the oligo-progressive disease lesion form was completed for 76 (93.8%) patients. There were 72 patients with available data entered on the CRF; of these, 67 (93.1%) patients achieved overall local control (PR/SD) according to oligo-progressive disease status at 6 months after SBRT (+/- 2 months).

Median OS following SBRT until death from any cause.

81 patients received SBRT treatment and were evaluable for this endpoint.

Number of patients who had an OS event following SBRT in the duration of the study. Overall survival definition is time from SBRT to death from any cause.

81 patients received SBRT treatment and were evaluable for this endpoint.

OS estimates following SBRT to death from any cause.

81 patients received SBRT treatment and were evaluable for this endpoint.

Median time following SBRT to alternative therapy administration or death.

81 patients received SBRT treatment and were evaluable for this endpoint.

Number of patients that started new treatment or died following SBRT in the duration of the study.

81 patients received SBRT treatment and were evaluable for this endpoint.

Time estimates from SBRT to alternative therapy administration or death.

81 patients received SBRT treatment and were evaluable for this endpoint.

Patient Reported Quality of Life assessed using the EuroQol (EQ) EQ-5D-5L questionnaire. VAS scale is from 0-100. A higher VAS score indicates better quality-of-life. Outcome data has been reported for (i) all completed assessments and for (ii) assessments conducted up to the point of disease progression, in order to exclude the potential influence of progression on quality-of-life outcomes.

81 patients who received SBRT treatment. Number analysed at each timepoint is the number of patients out of the 81 patients who were treated with SBRT, who had an available EQ-5D score at the respective timepoint. The left column reports results across all completed assessments for the patient population. The right column reports results only from assessments conducted prior to the occurrence of disease progression for all patients in the patient population.

Severity of acute and late side-effects resulting from SBRT assessed using the RTOG (Radiation Therapy Oncology Group) scoring criteria. A higher RTOG grade suggests higher severity of symptoms. Overall maximum grade for each patient at each timepoint is reported.

Of the 81 patients which had SBRT, the number of patients with an RTOG assessment at each respective visit is recorded. Results are reported up to 12 months post-SBRT as no toxicity assessments were reported at 18 and 24 months post-SBRT.

Severity of acute and late side-effects resulting from SBRT assessed using the Common Terminology Criteria for Adverse Events (CTCAE). A higher CTCAE grade suggests higher severity of symptoms. Overall maximum grade for each patient at each timepoint is reported.

Of the 81 patients which had SBRT, the number of patients with an CTCAE assessment at each respective visit is recorded. Results are reported up to 12 months post-SBRT as no toxicity assessments were reported at 18 and 24 months post-SBRT.

Prostate Specific Antigen (PSA) values recorded post-SBRT

Of the 81 patients who received SBRT treatment, 77 (95.1%) had both baseline and post-SBRT PSA results available, some of which were captured from PSA assessments following disease progression. Of the 77 patients with PSA results available, 40 (51.9%) patients either progressed or died within 6 months post-SBRT, whilst 37 (48.1%) patients did not progress or die within 6 months.