Adding androgen suppression (AS) to treatment with external-beam radiotherapy (EBRT) improved long-term outcomes in patients with intermediate-risk prostate cancer, according to study results published in the Journal of Clinical Oncology.
The phase 3 trial (ClinicalTrials.gov Identifier: NCT00021450) enrolled 481 patients with intermediate-risk prostate cancer.
The patients were randomly assigned to receive EBRT alone (n=236) or EBRT plus AS (n=245). In both arms, the EBRT dose level was 74 or 78 Gy. Patients in the AS arm received goserelin on day 1 of irradiation and then again 3 months later. Patients also received bicalutamide starting 1 week before the first goserelin injection.
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The primary endpoint was event-free survival (EFS). At a median follow-up of 12.2 years, the addition of AS significantly improved EFS. The 10-year EFS rate was 68.1% for the AS arm and 49.3% for the EBRT-alone arm (hazard ratio [HR], 0.53; 95% CI, 0.41-0.70; P <.001).
There was a significant improvement in disease-free survival (DFS) with AS as well. The 10-year DFS rate was 76.2% for the AS arm and 66.0% for the EBRT-alone arm (HR, 0.67; 95% CI, 0.49-0.90; P =.008).
The effect of AS on overall survival (OS) and distant metastasis-free survival (DMFS) did not reach statistical significance.
The 10-year DFMS rate was 79.3% in the AS arm and 72.7% in the EBRT-alone arm (HR, 0.74; 95% CI, 0.53-1.02; P =.065). The 10-year OS rate was 80.0% and 74.3%, respectively (HR, 0.74; 95% CI, 0.53-1.04; P =.082).
“These are the most robust data from a randomized trial with long-term follow-up…,” the study authors wrote. “They shed light on the important clinical question of the value of AS in men treated with radiation if dose escalation is used.”
Disclosures: This research was supported, in part, by AstraZeneca. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
Reference
Bolla M, Neven A, Maignon P, et al. Short androgen suppression and radiation dose escalation in prostate cancer: 12-year results of EORTC trial 22991 in patients with localized intermediate-risk disease. J Clin Oncol. Published online July 26, 2021. doi:10.1200/JCO.21.00855
