SPARC was a phase 2 trial that evaluated focal boost during prostate SBRT. It included 20 patients with unfavorable intermediate risk or high risk prostate cancer who had up to two dominant intraprostatic lesions (DILs) on MRI. All patients received ADT, and all were treated using CyberKnife. The prostate received 36.25 Gy in 5 fractions, and DILs were boosted up to 47.5 Gy. At 2 years, the cumulative rate of grade 2+ GU adverse events was 35%, and the rate of grade 2+ GI AEs was 5%. In PACE-B, the rate of grade 2+ GU AEs was 18.3% and GI was 7.8% at 2 years. Over the relatively brief follow up period, there was one biochemical relapse. | Yasar, Int J Radiat Oncol Biol Phys 2026
