Overview

• NRG-GU005 randomized 698 men with intermediate-risk localized prostate cancer to SBRT (36.25 Gy in 5 fractions) or moderately hypofractionated IMRT (70 Gy in 28 fractions or 60 Gy in 20).
• SBRT met the co-primary endpoint for bowel health, with fewer patients reporting clinically meaningful declines at two years vs. IMRT (34.9% vs. 43.8%; p=0.034).
• Disease-free survival at three years was lower with SBRT (88.6% vs. 92.1%), driven by higher biochemical (PSA) failures (7.8% vs. 4.2%; p=0.037), triggering a futility boundary for superiority.
• Local recurrence and three-year overall survival were essentially identical between groups (1.2% vs. 1.0% local recurrence; 97% OS each).
• Investigators noted fewer severe genitourinary complications with SBRT (0.6% vs. 2.5%) and reported that rectal spacers—used in roughly 55–56% of patients—reduced bowel side effects across both arms, with longer follow-up planned to clarify whether early PSA rises reflect durable progression and to assess SBRT dosing differences seen in other trials.