PURPOSE: ARTO (ClinicalTrials.gov identifier: NCT03449719 ) is a multicenter, phase II randomized clinical trial testing the benefit of adding stereotactic body radiation therapy (SBRT) to abiraterone acetate and prednisone (AAP) in patients with oligometastatic castrate-resistant prostate cancer (CRPC). MATERIALS AND METHODS: All patients were affected by oligometastatic CRPC as defined as three or less nonvisceral metastatic lesions. Patients were randomly assigned 1:1 to receive either AAP alone (control arm) or AAP with concomitant SBRT to all the sites of disease (experimental arm). Primary end point was the rate of biochemical response (BR), defined as a prostate-specific antigen (PSA) decrease ≥50% from baseline measured at 6 months from treatment start. Complete BR (CBR), defined as PSA < 0.2 ng/mL at 6 months from treatment, and progression-free survival (PFS) were secondary end points. RESULTS: One hundred and fifty-seven patients were enrolled between January 2019 and September 2022. BR was detected in 79.6% of patients (92% v 68.3% in the experimental v control arm, respectively), with an odds ratio (OR) of 5.34 (95% CI, 2.05 to 13.88; P = .001) in favor of the experimental arm. CBR was detected in 38.8% of patients (56% v 23.2% in the experimental v control arm, respectively), with an OR of 4.22 (95% CI, 2.12 to 8.38; P < .001). SBRT yielded a significant PFS improvement, with a hazard ratio for progression of 0.35 (95% CI, 0.21 to 0.57; P < .001) in the experimental versus control arm. CONCLUSION: The trial reached its primary end point of biochemical control and PFS, suggesting a clinical advantage for SBRT in addition to first-line AAP treatment in patients with metastatic castration-resistant prostate cancer.

Background and purpose: COVID-19 constitutes a worldwide threat, prompting Italian Government to implement specific measures on March 8, 2020, to protect patients and health workers from disease transmission. The impact of preventive measures on daily activity of a radiotherapy facility may hamper the ability to fulfill normal workload burden. Thus, we assessed the number of delivered treatments in a specific observation period after the adoption of preventive measures (since March 11 to April 24, 2020) and compared it with the corresponding period of the year 2019. Materials and methods: Overall number of delivered fractions was related to actual time of platform daily activity and reported as a ratio between number of delivered fractions and activity hours (Fr/Hrs). Fr/Hrs were calculated and compared for two different periods of time, March 11–April 24, 2019 (Fr/Hrs1), and March 11–April 24, 2020 (Fr/Hrs2). Results: Fr/Hrs1 and Fr/Hrs2 were 2.66 and 2.54 for year 2019 and 2020, respectively, for a Fr/Hrs^ratio of 1.07 (95% CI 1.03–1.12, p = 0.0005). Fr/Hrs1 was significantly higher than Fr/Hrs2 for Sli^R and Precise^R, with Fr/Hrs^ratio of 1.92 (95% CI 1.66–2.23, p < 0.0001) and 1.11 (95% CI 1.03–1.2, p = 0.003), respectively. No significant difference was reported for Synergy^R and Cyberknife^R with Fr/Hrs^ratio of 0.99 (95% CI 0.91–1.08, p = 0.8) and 0.9 (95% CI 0.77–1.06, p = 0.2), respectively. Fr/Hrs1 was significantly lower than Fr/Hrs2 for Tomotherapy^R, with Fr/Hrs^ratio of 0.88 (95% CI 0.8–0.96, p = 0.007). Conclusion: Preventive measures did not influence workload burden performed. Automation in treatment delivery seems to compensate effectively for health workers number reduction.