Clinical Outcomes of Stereotactic Body Radiotherapy With Immediate Versus Delayed Hormone Therapy in Men With Oligometastatic Recurrence of Prostate Cancer

Stereotactic body radiotherapy (SBRT) with the delayed option of androgen deprivation therapy (ADT) is the current treatment paradigm in men relapsed with oligometastatic prostate cancer based on the outcome of a phase II randomised controlled study. The immediate (concomitant) use of ADT in this clinical setting potentially augments the efficacy of SBRT by improving systemic disease control. The aim of this study was to compare the clinical outcomes of these two treatment strategies. Eighty-eight patients with up to three oligometastases and controlled primary disease who had been treated using SBRT with immediate or delayed ADT were included in this retrospective analysis. Progression-free survival (PFS), widespread failure-free survival (WFFS) and freedom from further interventions (FFFI) were assessed using Kaplan–Meier and Cox proportional hazard regression methods. Toxicity was evaluated using Common Terminology Criteria for Adverse Events (CTCAE) v4.0. Thirty-nine patients (44.3%) were treated with SBRT and immediate ADT (continuous ADT, n = 7; intermittent ADT, n = 32) and 49 (55.7%) with SBRT and delayed ADT. The median follow-up was 24 months (interquartile range 13.5–37.0 months). PFS in the immediate and delayed ADT groups were 26 months and 16 months, respectively (P