Eligible patients are those with either primary breast, prostate or NSCLC who have presented with ≤3 extra-cranial, metachronous, oligometastases, all suitable for SBRT. Patients will be randomised in a 1:1 ratio to either SOC or SOC with the addition of SBRT. Choice of SOC treatment is at the discretion of the local oncologist and defined per patient prior to randomisation (see section 8). Patients randomised to SBRT+SOC will receive a dose and fractionation regimen dependent on the metastatic site and proximity to dose limiting organs and normal tissues. Treatment will take place within 6 weeks of randomisation. The average scheme would be 3 treatments over 5 days but the maximum period of SBRT duration could be 8 treatments over 19 days.