Stereotactic Body Radiation Therapy May Benefit Patients With Oligometastatic Castration-Resistant Prostate Cancer

According to the phase 2 ARTO trial, there is a clinical advantage from the addition of stereotactic body radiation therapy (SBRT) to first-line abiraterone acetate and prednisone treatment among patients with metastatic castration-resistant prostate cancer.

This trial enrolled 157 patients with oligometastatic castration-resistant prostate cancer (≤3 nonvisceral metastatic lesions) between January 2019 and September 2022. Patients were randomly assigned on a 1-to-1 basis to receive either abiraterone acetate and prednisone alone (n = 82, control arm) or abiraterone acetate and prednisone with concomitant SBRT to all sites of disease (n = 75, experimental arm). The primary end point was the rate of biochemical response, which was defined as a decrease of prostate-specific antigen (PSA) of at least 50% from the baseline. Secondary end points were complete biochemical response, defined as a PSA < 0.2 ng/mL measured at 6 months from treatment, and progression-free survival.

The rate of biochemical response was 92% in the experimental arm vs 68.3% in the control arm (odds ratio [OR], 5.34; 95% confidence interval [CI], 2.05 to 13.88; P = .001). Complete biochemical response was occurred in 56% of patients in the experimental arm and 23.2% of patients in the control arm (OR, 4.22; 95% CI, 2.21 to 8.39; P < .001). In the experimental arm, median progression-free survival was not reached, compared with 17 months in the control arm (progression: hazard ratio, 0.35; 95% CI, 0.21 to 0.57; P < .001).

Dr Francolini, Careggi University Hospital, Florence, Italy, and coauthors concluded this trial “suggests that patients treated with concomitant SBRT and abiraterone acetate may have significant advantage in terms of PSA reduction at 6 months and progression-free survival when compared with patients treated with standard systemic treatment…without any meaningful signal of increased rate of adverse events.”

Journal of Clinical Oncology associate editor Michael Carducci, MD, Johns Hopkins Medicine, Baltimore, Maryland, noted, “These results should be confirmed in larger studies and placed into context with the changing landscape of treatment options for metastatic hormone sensitive and metastatic castration resistant disease.”

Source:

Francolini G, Gaetano Allegra A, Detti B, et al. Stereotactic body radiation therapy and abiraterone acetate for patients affected by oligometastatic castrate-resistant prostate cancer: A randomized phase II trial (ARTO). J Clin Oncol. Published online September 21, 2023. doi:10.1200/JCO.23.00985