Adding metastasis-directed therapy via stereotactic body radiotherapy (SBRT) to standard abiraterone acetate and androgen-deprivation therapy (ADT) significantly improves overall survival in patients with oligometastatic castration-resistant prostate cancer. According to a long-term analysis of the phase II ARTO trial published in The Lancet Oncology, patients receiving SBRT experienced superior survival rates and delayed disease progression compared to those treated with systemic therapy alone.
Survival Outcomes in the ARTO Trial
The ARTO trial, an open-label, multicenter study, evaluated 157 patients with no more than three metastatic sites who had not previously received treatment for metastatic disease. Researchers randomly assigned participants to receive either ADT plus abiraterone acetate alone or in combination with SBRT targeting all metastatic sites. The radiation protocol utilized one to five fractions, delivering a biologically effective dose of at least 100 Gy.
After a median follow-up of 53 months, the survival data favored the SBRT cohort. The median overall survival was 50 months for the control group, while the median survival for the SBRT group had not yet been reached (hazard ratio [HR] = 0.55; 95% CI = 0.33–0.92; P = .021). These findings, reported by Giulio Francolini, MD, and colleagues, indicate a measurable survival advantage when local ablation is integrated with systemic treatment.
The ARTO trial showed that the SBRT group maintained a median biochemical progression–free survival of 44 months, compared to just 18 months for patients receiving only systemic therapy.
Disease Progression and Safety Profiles
Beyond overall survival, the integration of SBRT demonstrated a significant impact on disease control. The study reported a median radiologic progression–free survival of 44 months in the SBRT arm, contrasted with 17 months in the control group (HR = 0.48; 95% CI = 0.32–0.72; P < .001). This suggests that targeting metastatic lesions early can effectively delay the time until the disease spreads further or shows signs of resistance.
Safety data provided by the investigators showed that the SBRT group experienced fewer severe adverse events. Grade 3 or worse adverse events were recorded in 12% of the SBRT group, compared to 24% of the control group. The control group saw more infectious complications and blood test abnormalities, whereas cardiovascular disorders were reported at similar rates in both groups. One treatment-related death occurred in the control group due to myocardial failure.
Future Trends in Prostate Cancer Care
Frequently Asked Questions
What was the primary benefit of adding SBRT to systemic therapy?
The addition of SBRT resulted in a significant improvement in overall survival, with a hazard ratio of 0.55 compared to systemic therapy alone, according to findings from the ARTO trial.
How does SBRT affect disease progression?
Patients receiving SBRT experienced significantly longer median biochemical and radiologic progression–free survival (44 months each) compared to the control group (18 and 17 months, respectively).
Were there increased side effects with the addition of SBRT?
No. In the ARTO trial, grade 3 or worse adverse events were actually lower in the SBRT group (12%) than in the control group (24%).
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