A PHASE 1/2 clinical trial has reported encouraging early outcomes for single-fraction stereotactic body radiotherapy (SBRT) in men with localised prostate cancer, suggesting that a single high-dose treatment may provide effective disease control with acceptable toxicity.
The multicentre prospective nonrandomised study evaluated whether a single 19-Gy dose of prostate SBRT could achieve biochemical control while maintaining safety and quality of life.
The study included men with low- or intermediate-risk prostate cancer, with International Society of Urological Pathology grade group 1 or 2 disease and no significant tumour involvement of the transitional zone. Of the 45 patients enrolled, 43 received treatment according to protocol. Participants had a median age of 72 years and were followed for a median of 55.3 months.
Single-Fraction SBRT Shows Encouraging Outcomes in Localised Prostate Cancer
Patients were treated with a single 19-Gy SBRT fraction using urethra-sparing techniques and real-time control of prostate movement during treatment. The primary endpoint was 3-year biochemical relapse-free survival (bRFS), with the study designed to test whether outcomes could meet a predefined threshold.
At three years, estimated bRFS was 92.9% (95% CI, 85.4%-100%), meeting the trial’s primary endpoint. The researchers reported that treatment-related adverse events remained low, supporting the tolerability of this approach.
Low Rates of Urinary and Gastrointestinal Toxicity Reported Following SBRT
Grade 2 genitourinary (GU) adverse events occurred in 9.8% of patients and grade 2 gastrointestinal (GI) events occurred in 4.9% at three years. One patient experienced grade 3 proctitis at 12 months. Sexual function outcomes showed a greater impact, with grade 2 or higher erectile dysfunction increasing from 21.4% at baseline to 38.4% at three years.
Quality-of-life assessments demonstrated limited deterioration, with clinically meaningful changes observed in GU scores in 14% of patients and sexual scores in 28%. Gastrointestinal quality-of-life effects were minimal.
The authors concluded that single-fraction 19-Gy urethra-sparing SBRT appears feasible and well tolerated in carefully selected patients with localised prostate cancer. However, they emphasised that longer follow-up is required to determine whether this approach provides durable long-term cancer control.
If confirmed in larger comparative studies, single-session SBRT could represent a further evolution in prostate cancer radiotherapy, reducing treatment burden while maintaining oncological outcomes.
Reference
Zilli T et al. Single-fraction stereotactic body radiotherapy for localized prostate cancer: a nonrandomized clinical trial. JAMA Oncol. 2026; DOI: 10.1001/jamaoncol.2026.1886.
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