Background
Phase II RCT (ORIOLE). 54 patients with recurrent hormone-sensitive prostate cancer and 1–3 radiographically visible metastases (on conventional imaging) without systemic therapy. Randomized 2:1 to observation vs SBRT to all visible metastatic lesions. Primary aim: assess whether SBRT delays disease progression in oligometastatic hormone-sensitive prostate cancer.
Interventions and follow up
Arm A: SBRT to all visible metastases (dose 19.5 Gy × 3 fractions; bone/node sites; 36 patients)
Arm B: Observation — 18 patient
Primary endpoint: Progression at 6 months (PSA or clinical progression)
mFollow up: 18.8 month
Arm B: Observation — 18 patient
Primary endpoint: Progression at 6 months (PSA or clinical progression)
mFollow up: 18.8 month
Results
Progression at 6 months (SBRT): 19% vs observation 61%, P=.005
mPFS (SBRT): Not reached vs 5.8 months (observation), P=.002
PSMA PET sub-study: Patients with all lesions treated (PSMA-concordant SBRT) had better outcomes (mPFS NR vs 11.8 mo, P=.006)
mPFS (SBRT): Not reached vs 5.8 months (observation), P=.002
PSMA PET sub-study: Patients with all lesions treated (PSMA-concordant SBRT) had better outcomes (mPFS NR vs 11.8 mo, P=.006)
Adverse events
Main adverse events: Grade ≥2 toxicity: SBRT 6% — primarily fatigue and musculoskeletal pain. No grade ≥3 adverse events. No treatment-related serious adverse events.
Conclusions
SBRT to all visible oligometastatic lesions significantly reduced progression at 6 months and improved PFS in recurrent hormone-sensitive prostate cancer. The PSMA PET sub-analysis suggests that occult disease not visible on conventional imaging may account for failures — PSMA PET staging may improve patient selection.
Key Limitations
Key Limitations: Small sample size (54 patients). Short follow-up. Progression defined partly by PSA — not an OS endpoint. PSMA PET sub-study hypothesis-generating only. Observation arm received no systemic therapy — unclear if ADT would negate benefit of SBRT or whether SBRT delays need for ADT.
Clinical Context
ORIOLE (with STOMP) supports SBRT as a metastasis-directed therapy (MDT) option in oligometastatic hormone-sensitive prostate cancer to delay systemic therapy. PSMA PET is increasingly used to guide MDT patient selection. Current phase III trials (EXTEND) are investigating whether MDT delays initiation of ADT and improves quality of life.
References