As reported in The Lancet Oncology by Francolini et al, an unplanned long-term analysis of overall survival in the Italian phase II ARTO trial showed a survival benefit with the addition of metastasis-directed therapy with stereotactic body radiotherapy (SBRT) to abiraterone acetate and androgen-deprivation therapy (ADT) in patients with oligometastatic castration-resistant prostate cancer.
Study Details
In the multicenter open-label trial, 157 patients with no more than three metastatic sites and no prior treatment for metastatic disease were randomly assigned between January 2019 and September 2022 to receive ADT plus abiraterone acetate at 1,000 mg daily with (n = 75) or without (n = 82) SBRT to all sites of metastatic disease; SBRT consisted of one to five fractions providing a biologically effective dose ≥ 100 Gy. The primary analysis of the trial showed improved 6-month biochemical response in the SBRT group. The current analysis aimed to explore the effect of metastasis-directed therapy on overall survival.
Key Findings
After a median follow-up of 53 months (interquartile range = 43–60 months), median overall survival was 50 months (95% confidence interval [CI] = 36 months to not reached) in the control group vs not reached (95% CI = 55 months to not reached) in the SBRT group (hazard ratio [HR] = 0.55, 95% CI = 0.33–0.92, P = .021).
Median biochemical progression–free survival was 44 months in the SBRT group vs 18 months in the control group (HR = 0.49, 95% CI = 0.33–0.72, P < .001). Median radiologic progression–free survival was 44 months vs 17 months (HR = 0.48, 95% CI = 0.32–0.72, P < .001).
Overall, adverse events of grade 3 or worse occurred in 24% of the control group vs 12% of the SBRT group; the most common grade 3 to 4 adverse events were infectious complications (five patients in the control group vs none in the SBRT group), cardiovascular disorders (three vs three), and blood test abnormalities (four vs one). One treatment-related death occurred in the control group (due to myocardial failure).
The investigators concluded: “The ARTO trial showed significant benefit in overall survival with the addition of [metastasis-directed therapy] to systemic therapy versus systemic therapy alone.”
Giulio Francolini, MD, of Radiation Oncology Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy, is the corresponding author for The Lancet Oncology article.
DISCLOSURE: The study was funded by Fondazione Radioterapia Oncologica. For full disclosures of the study authors, visit thelancet.com.
