The long-term ARTO analysis suggests that adding stereotactic body radiotherapy to abiraterone acetate and androgen deprivation therapy may improve survival in selected patients with oligometastatic castration-resistant prostate cancer.
The article, titled “SBRT plus abiraterone acetate and ADT versus abiraterone acetate and ADT in oligometastatic castrate-resistant prostate cancer (ARTO): long-term, unplanned overall survival analysis of an open-label, randomised, phase 2 trial,” was published in The Lancet Oncology, Volume 27, Issue 7, July 2026.
Authors: Giulio Francolini, Vanessa Di Cataldo, Saverio Caini, Pietro Garlatti, Michele Aquilano, Niccolò Bertini, Alessio Bruni, Gianluca Ingrosso, Rolando M. D’Angelillo, Luca Tagliaferri, Barbara A. Jereczek-Fossa, Matteo Augugliaro, Luca Triggiani, Silvana Parisi, Lorenzo Masieri, Riccardo Campi, Richard K. Valicenti, Gabriele Simontacchi, Daniela Greto, Pierluigi Bonomo, Mauro Loi, Chad Tang, and Lorenzo Livi, on behalf of the ARTO Working Group.
Background
Metastasis-directed therapy with stereotactic body radiotherapy has become an important strategy in oligometastatic prostate cancer. Previous randomized studies have shown that SBRT can delay progression in selected patients, especially in metastatic hormone-sensitive disease.
In metastatic castration-resistant prostate cancer, its long-term role has remained less clear. Patients with a limited number of metastatic lesions may have a more indolent disease course, raising the question of whether treating all visible sites of disease could improve outcomes when added to systemic therapy.
The initial ARTO analysis showed improved biochemical response and progression-free survival with SBRT plus abiraterone and androgen deprivation therapy. This long-term analysis evaluated whether that benefit translated into improved overall survival.
Read more about Prostate Cancer Remission Rate on OncoDaily.
ARTO Trial
ARTO was a multicenter, open-label, randomized phase 2 trial conducted in 16 academic and community centers in Italy. The trial included patients with metastatic castration-resistant prostate cancer, no more than 3 non-visceral nodal or bone metastases, and no previous systemic therapy for metastatic castration-resistant disease. The trial is registered as NCT03449719.
Overall, 157 patients were randomly assigned to receive abiraterone acetate plus prednisone and androgen deprivation therapy alone, or the same systemic therapy with SBRT to all metastatic sites.
The original primary endpoint was 6-month biochemical response. This report focused on long-term overall survival, biochemical progression-free survival, radiological progression-free survival, prostate cancer-specific survival, and safety.
Results
After a median follow-up of 53 months, 65 patients had died: 41 in the control group and 24 in the SBRT group. Median overall survival was 50 months with abiraterone acetate and androgen deprivation therapy alone and was not reached with the addition of SBRT.
The addition of SBRT was associated with a significant overall survival benefit:
- HR 0.55; 95% CI, 0.33–0.92; p=0.021.
Prostate cancer was the primary cause of death in 35 patients, including 25 in the control group and 10 in the SBRT group. In a post-hoc analysis, 4-year prostate cancer-specific survival was 67.7% in the control group and 86.6% in the SBRT group.
Progression-free outcomes also favored SBRT. Median biochemical progression-free survival was 44 months with SBRT versus 18 months in the control group. Median radiological progression-free survival was 44 months versus 17 months, respectively.
Safety
The addition of SBRT did not raise new safety concerns. Any-grade adverse events were reported in 40 patients in the control group and 33 patients in the SBRT group. Grade 3 or worse adverse events occurred in 20 patients in the control group and 9 patients in the SBRT group.
The most common grade 3–4 adverse events were infectious complications, reported in 5 patients in the control group and none in the SBRT group; cardiovascular disorders, reported in 3 patients in each group; and other blood test abnormalities, reported in 4 patients in the control group and 1 patient in the SBRT group.
One treatment-related death due to myocardial failure occurred in the control group. No treatment-related deaths were reported in the SBRT group. Adverse events potentially related to SBRT, including lower urinary tract symptoms, fractures, hematuria, gastrointestinal disorders, and back pain, were not significantly increased in the SBRT group.
Conclusion
The long-term ARTO analysis suggests that adding stereotactic body radiotherapy to abiraterone acetate and androgen deprivation therapy may improve survival in selected patients with oligometastatic castration-resistant prostate cancer.
Although the survival analysis was unplanned and the trial was originally powered for biochemical response, these results support further phase 3 evaluation of early metastasis-directed therapy in this setting.
The full article is available in The Lancet Oncology.