Stereotactic ablative radiotherapy (SABR) is superior to observation for preventing disease progression in men with recurrent hormone-sensitive oligometastatic prostate cancer, according to results from the phase II ORIOLE trial. Fifty-four patients were randomly allocated (2:1) to receive SABR or undergo observation. The primary outcome measure was progression at 6 months, defined by PSA increase, conventional imaging, symptomatic progression, initiation of androgen deprivation therapy or death. Progression occurred in 19% of patients receiving SABR compared with 61% undergoing observation (P = 0.005), and SABR improved median progression-free survival compared with observation (not reached vs 5.8 months; HR 0.30, 95% CI 0.11–0.81; P = 0.002).