ARTO Trial Final Results: Long-Term Survival Benefit of SBRT Added to Abiraterone in Oligometastatic mCRPC

The phase 2 ARTO trial findings, published on The Lancet, provides stronger evidence that metastasis-directed SBRT can improve outcomes in oligometastatic castration-resistant prostate cancer. In this randomized study, 157 patients were enrolled across 16 academic and community centers in Italy and assigned 1:1 to abiraterone plus ADT with or without SBRT to all visible metastatic sites.

After a median follow-up of 53 months, median overall survival was 50 months in the control arm and not reached in the SBRT arm, with a hazard ratio for death of 0.55 and a p value of 0.021. The trial also reported no clear excess in serious toxicity from adding radiation, while the most common grade 3–4 events were infectious complications in the control arm and cardiovascular events in both arms at similar low frequency.

The broader message is that the benefit was not just early biochemical control. ARTO had already shown improved PSA response and progression-free outcomes, and the long-term analysis now suggests those gains may extend to survival, with a clinically meaningful separation between the two arms over nearly 4.5 years of follow-up.

In a disease setting where proving an OS advantage is difficult, that is a notable signal that combining systemic therapy with targeted radiation may be better than systemic therapy alone in the right oligometastatic mCRPC patients.

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