Single-Fraction Stereotactic Body Radiotherapy for Localized Prostate Cancer
Year: 2026
Type: article
Study design: Clinical Trial
Abstract: Importance: Stereotactic body radiotherapy (SBRT), most commonly delivered in 5 fractions, is an established treatment option for patients with localized prostate cancer. While efforts to further reduce treatment to fewer than 5 fractions are ongoing, the efficacy and tolerability of single high-dose SBRT remain to be established. Objective: To determine in men with localized prostate cancer whether a single-fraction SBRT can be a valid treatment option in terms of biochemical disease control and safety. Design, Setting, and Participants: This multicenter, single-arm, prospective, phase 1/2 nonrandomized clinical trial included men with localized prostate cancer at low or intermediate risk, with International Society of Urological Pathology grade group 1 or 2, and without significant tumor in the transitional zone. Participants were recruited between 2017 and 2022 in 5 academic centers in Europe and the US. Data were analyzed between February and May 2026. Intervention: Participants were treated with a 19-Gy single-fraction prostate SBRT with urethra-sparing and intrafraction motion control. Main Outcomes and Measures: The primary end point was biochemical relapse-free survival (bRFS) at 3 years (expected value of 96% included in the 95% CI). Secondary end points included occurrence of genitourinary (GU), gastrointestinal (GI), and sexual adverse events (AEs) and quality of life (QOL) assessment. Results: Among the 45 patients recruited (median age, 72 [range, 60-82] years), 43 were treated per protocol. After a median follow-up of 55.3 (IQR, 49.9-60.7) months, the estimated 3-year bRFS was 92.9% (95% CI, 85.4%-100%), meeting the primary end point. At 3 years, grade 2 GU and GI AEs were observed in 4 (9.8%) and 2 (4.9%) participants, respectively, with only a grade-3 proctitis observed in 1 patient at month 12. Grade 2 or higher erectile dysfunction increased from 9 of 42 patients (21.4%) at baseline to 15 of 39 (38.4%) at 3 years. A significant minimally clinically important change in Expanded Prostate Cancer Index Composite scores was observed in 6 (14%) and 12 (28%) participants for GU and sexual scores, respectively. The impact in GI bother scores was minimal. Conclusions and Relevance: In this multicenter phase 1/2 trial, a single-fraction 19-Gy urethra-sparing SBRT met the primary end point, achieving a 3-year bRFS of 92.9%, with grade 2 GU and GI AEs remaining below 10% and 5%, respectively, at 3 years. Longer follow-up is warranted to assess long-term disease control. Trial Registration: ClinicalTrials.gov Identifier: NCT03294889.
Source: JAMA Oncology
Institutions: University of Geneva, Ente Ospedaliero Cantonale, University Hospital of Geneva, Istituto Oncologico della Svizzera Italiana, Università della Svizzera italiana, Humanitas University, IRCCS Humanitas Research Hospital, University of Zurich, University Hospital Zurich, Ospedale Sacro Cuore Don Calabria, Institut Bergonié, Centre Hospitalier Universitaire de Saint-Étienne, Université Jean Monnet, University of Alabama at Birmingham, O'Neal Comprehensive Cancer Center, University of Brescia, Centre Georges François Leclerc
Language: English
Subfield: Pulmonary and Respiratory Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7165164305