[Correspondence] SBRT in oligometastatic castration-resistant prostate cancer

The Article by Tamim Niazi and colleagues1 on the Prostate Cancer Study 9 (PCS-9) investigated stereotactic body radiotherapy (SBRT) with androgen receptor pathway inhibitors (ARPIs) in oligometastatic castration-resistant prostate cancer (mCRPC). This study is the second randomised trial, after the ARTO trial,2 to evaluate this combination. Both PCS-9 and ARTO showed improved radiographical progression-free survival with SBRT. However, a significant biochemical response benefit was only observed in the ARTO study, possibly reflecting differences in disease burden (baseline prostate-specific antigen was 3·4 ng/mL in ARTO vs ~10 ng/mL in PCS-9) and imaging strategies, with molecular imaging in ARTO likely identifying earlier disease.