ESTRO 2025 - Abstract Book

S401

Brachytherapy - Urology

ESTRO 2025

Results: Freedom from BCF rates among patients with a DIL located in the posterior midgland were statistically significantly higher compared to patients with DILs located in other sectors (HR 0.4, 95% CI 0.2-0.7, p = 0.002). Anterior right and left base sectors were associated with higher rates of BCF versus other sectors with respective 5-year rates of freedom from BCF of 76.7% (HR 5.4, 95% CI 1.7-17.0, p=0.004) and 49.1% (HR 9.6, 95% CI 2.9-31.3, p=0.0002). Multivariate analysis (MVA) of freedom from BCF accounting for the plus-shaped sector containing the DIL, Gleason score (GS), iPSA and prostate gland size demonstrated statistically significant HR for the anterior left base (HR 4.3, p=0.0002), and anterior right base (HR 2.7, p=0.02). In a similar MVA of freedom from BCF accounting for the cross shaped sector containing the DIL, the HR for the posterior midgland sector also reached statistical significance (HR 0.2, p=0.02). These findings persisted when the D90 to the DIL was included in the MVA for both methods of prostate sector division, suggesting that both the location of the DIL within the prostate gland, and the D90 received by that sector were predictive of BCF, independent of GS, iPSA and gland size.