Impact of magnetic resonance imaging visibility of prostate cancer on partial gland ablation.

Objectives: To evaluate the outcomes of partial gland ablation (PGA) according to prostate cancer (PCa) visibility on magnetic resonance imaging (MRI). Subjects and Methods: Consecutive patients with localized PCa diagnosed by MRI-informed prostate biopsy (PBx), who underwent hemi-gland Cryoablation (CRYO) or hemi-gland High-Intensity Focused Ultrasound (HIFU), were identified from a multicentric database. High-visibility was defined as Prostate Imaging-Reporting and Data System (PIRADS) ≥ 4. The primary endpoint was treatment failure (TF), defined as Grade Group (GG) ≥ 2 on follow-up PBx (FU-PBx), any whole-gland treatment, systemic therapy, metastases or PCa-specific mortality. Kaplan-Meier and Cox regression analyses were performed. Statistically significant if p < 0.05. Results: A total of 156 patients met the inclusion criteria being 96 (62%) high-visibility and 59 (38%) low-visibility groups on baseline MRI. The baseline characteristics were as follows: median age 65yo, prostate-specific antigen (PSA) 6.0 ng/ml, 22% with PIRADS 1-2, 16% with PIRADS 3, 44% with PIRADS 4 and 17% with PIRADS 5. The 3-year free-survival rates for high-visible vs low-visible were: TF 57% vs 83% (p = 0.002); biochemical failure (PSA nadir + 2 ng/ml) 81% vs 72% (p = 0.5); GG ≥ 2 on FU-PBx 57% vs 85% (p < 0.001); and Radical Treatment 87% vs 85% (p = 0.9), respectively. After adjusting for confounders, the independent predictors for TF were PSA density, PSA reduction and high visibility (hazard ratio 4.83, 95% confidence interval 1.81-12.90). Conclusion: MRI visibility is an independent prognosticator for outcomes following focal therapy for prostate cancer. Patients with higher MRI visibility (PIRADS ≥4) are at an increased risk of treatment failure.