Salvage Metastasis-Directed Therapy Without Androgen Deprivation for Positron Emission Tomography–Defined Oligorecurrent Prostate Cancer: Results of the SOAR Phase II Trial
Evan Crockett, Bogdana Schmidt, Olivia Rodriguez, Adam Taylor, Emma Braun, Samuel Leonhart, Umang Swami, Kenneth M. Boucher, Lisa Chapman, Hillary Davis, Jeff Linton, Erica Mangelson, Skyler Johnson, Jonathan Tward, Bismarck Odei, Jeff Yap, Sumati Gupta, Manish Kohli, Neeraj Agarwal, Christopher Dechet, Brock O'Neil, Benjamin L. Maughan, Alejandro SanchezPurpose:
Advanced molecular imaging has enabled detection of oligorecurrent prostate cancer (PCa) at low PSA levels, but optimal management of positron emission tomography (PET)–defined recurrence remains uncertain. We conducted a phase II trial to evaluate biochemical response, oncologic outcomes, and safety of salvage metastasis-directed therapy (MDT) delivered without concurrent androgen deprivation therapy (ADT).
Materials and Methods:
Twenty men with PET-defined oligometastatic recurrence (≤ 10 nodal or osseous lesions) after radical prostatectomy were prospectively enrolled (2019-2023). Treatment was assigned based on disease distribution: bone-directed radiotherapy (arm A), salvage lymph node dissection (sLND; arm B), or combined therapy (arm C). The primary endpoint was a ≥ 50% PSA decline at 6 months; secondary endpoints included PSA progression, ADT-free survival, and treatment-related morbidity.
Results:
The median age was 65 years (IQR 61.5-70.0); 18 patients had nodal-only recurrence, and 2 had bone-only disease. At 6 months, 8 of 20 patients (40%) achieved ≥ 50% PSA reduction. Over a median follow-up of 11.4 months, 12-month PSA-PFS was 74.1% (95% confidence interval [CI] 54.8%-100%) and ADT-free survival was 71.4% (95% CI 52.7%-96.6%), with a median of 13.3 months. Among sLND patients, pathologic carcinoma was confirmed in 15 of 18 (83%) and pathologic assessment frequently revealed more extensive nodal disease than predicted by PET. No Clavien-Dindo grade III-V complications occurred.
Conclusions:
Salvage MDT without ADT is feasible, safe, and associated with meaningful biochemical responses in selected patients with PET-defined oligorecurrent PCa. Pathologic findings demonstrate that PET imaging may underestimate true nodal disease burden, supporting comprehensive treatment strategies and further prospective investigation.