Background: ARTO (NCT03449719) is a multicentre, randomized phase II trial testing the benefit of concomitant stereotactic body radiation therapy (SBRT) and abiraterone acetate (AA)+ prednisone administration in oligometastatic Castrate Resistant Prostate Cancer (CRPC) patients. Results already showed significant benefit in terms of biochemical response and Progression Free Survival (PFS) in the experimental arm. To explore role of local treatment throughout the whole clinical history of these patients, here is reported a subgroup analysis focusing on impact of treatment (SBRT vs second line systemic therapy) after progression. Methods: Patients affected by oligometastatic CRPC (</= 3 non-visceral metastatic lesions) were enrolled in the trial and randomized 1:1 to receive either AA+ prednisone alone (control arm) or associated with concomitant SBRT on all sites of disease (treatment arm). PFS2 was defined as time between first progression event and second progression, death or last follow up. Cox regression analysis was performed to compare PFS2 in patients treated with SBRT on oligo-progressive metastatic sites vs patients undergoing second line systemic therapy (primarily taxane chemotherapy). Results: One hundred fifty-seven patients were enrolled in ARTO trial. At last follow up (August 2023), 77 patients progressed after abiraterone+ prednisone treatment (23 vs 54 in the experimental vs control arm, respectively). Of these, 14 received best supportive care and were excluded from the analysis, 23 underwent SBRT on oligo-progressive metastatic sites (17 and 6 originally randomized to the experimental vs control arm, respectively), 40 were treated with second line systemic treatment. A second progression event was detected in 14 patients. Median PFS 2 was 10 months (95% CI 10-17) and 10 months (95% CI 7-12) for patients undergoing SBRT vs second line treatment, respectively (HR 1.26, 95% CI 0.33-4.75, p 0.73). Conclusions: When oligoprogressive status is detected, SBRT may achieve similar benefit if compared to second line systemic treatment. These data, in the context of a randomized trial with positive results for primary endpoints, suggest that repeated SBRT may be a viable treatment option in selected patients. Clinical trial information: NCT03449719.