Phase 2 SOAR Trial: Treating Oligorecurrent Prostate Cancer Without ADT Shows Promise

The phase II SOAR trial suggests that metastasis-directed therapy (MDT) alone may delay the need for androgen deprivation therapy in carefully selected men with PET-defined oligorecurrent prostate cancer. Twenty patients with up to ten nodal or bone metastases after radical prostatectomy received radiotherapy, salvage lymph-node dissection, or both, without concurrent ADT. At six months, 40% achieved a PSA reduction of at least 50%, while estimated 12-month PSA progression-free survival was 74.1% and ADT-free survival 71.4%.

The study is small and its population was heavily weighted toward nodal recurrence: 18 of the 20 patients had nodal-only disease, while only two had bone-only metastases. This is an important limitation, as the results cannot automatically be extrapolated to patients with predominantly osseous oligometastatic recurrence or more biologically aggressive metastatic disease.

However, one finding may be particularly important: among men undergoing lymph-node dissection, pathology frequently revealed more extensive disease than had been detected by PET imaging. This reinforces an emerging concern in the PSMA-PET era: visible oligometastatic disease may represent only part of the true tumour burden.

Together with trials such as ORIOLE, RADIOSA and PEACE V-STORM, SOAR supports the idea that treating all detectable disease, and possibly the wider anatomical regions at risk of microscopic spread, could meaningfully delay progression. The future role of MDT may therefore be less about replacing systemic treatment and more about reducing residual disease as completely as possible while preserving quality of life and delaying further therapy where appropriate.

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