Advancing Treatment in Oligometastatic Castration-Resistant Prostate Cancer: The GROUQ-PCS 9 Trial on SBRT Plus Standard Systemic Therapy

Highlight

– The phase 2 GROUQ-PCS 9 trial shows that adding stereotactic body radiotherapy (SBRT) to standard systemic therapy (ADT plus enzalutamide) significantly doubles median radiographic progression-free survival (rPFS) in men with oligometastatic castration-resistant prostate cancer (CRPC).
– The trial enrolled 102 patients across 13 Canadian oncology centers with ≤5 metastases and demonstrated an rPFS of 4.6 years with SBRT addition compared to 2.3 years with systemic therapy alone.
– No new safety concerns were identified; both treatment arms had comparable toxicity profiles with impotence being the most common grade 3 treatment-related adverse event.
– These findings support integrating metastasis-directed therapy into management of oligometastatic CRPC to prolong disease control.

Study Background and Disease Burden