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.