CyberKnife Ultra-Hypofractionated SBRT for Localized Prostate Cancer with Dose Escalation to the Dominant Intraprostatic Lesion: In Silico Planning Study

The aim is to evaluate the feasibility of ultra-hypofractionated (UH) SBRT with CyberKnife® (CK) radiosurgery (Accuray Inc., Sunnyvale, California, USA) for localized prostate cancer (PCa) a concomitant focal boost dominant intraprostatic lesion (DIL). Patients intermediate/high-risk PCa, at least one visible DIL on multi-parametric MRI, were included. For each, two CK-SBRT in silico plans calculated using 95% and 85% isodose lines (CK-95%, CK-85%) compared UH-DWA plan delivered VERO®. All simulated SIB prescription 40 Gy PTV-DIL 36.25 whole (PTV-prostate) five fractions every other day. Fifteen patients considered. reached primary planning goal (D95% > 95%) compliance organs risk (OARs) constraints. DVH metrics median values increased (p < 0.05) from CK-85%. conformity index was 1.00 all techniques, while PTV-prostate 0.978, 0.984, 0.991 UH-DWA, CK-95%, CK-85%, respectively. CK-85% able reach maximum dose 47 respecting OARs plus PCa appears be feasible. These encouraging dosimetric results are confirmed upcoming clinical trials such as phase-II “PRO-SPEED” IEO trial.