Introduction:

There is increasing interest in focal gland ablation for the treatment of intermediate risk prostate cancer. However, criteria used to define suitable patients for focal therapy have varied widely, despite the existence of consensus statements (Tay, Prostate Cancer Prostatic Dis 2017) as guides. We aim to evaluate a prospective cohort of men undergoing transrectal MRI fusion-guided biopsy for detection of prostate cancer with the goal of defining eligibility criteria for intermediate risk disease in our focal therapy protocol.

Methods:

Patients who underwent MRI/ultrasound image fusion biopsy between 10/2014-2/2020 were identified within a prospectively maintained database. For the purposes of this study, we defined “Eligibility” for focal therapy as Grade Group (GG) 2 or 3 within an MRI defined region of interest (ROI). Patients remained eligible if systematic random biopsies at time of targeted biopsy were benign or contained <4mm GG1. Exclusion criteria included GG4 or 5 disease in any core, or GG1 only disease. Patient demographics and clinicopathologic features are reported along with percent eligible using descriptive statistics.

Results:

Out of 1,513 total patients captured, 1,351 contained a biopsy of GG1-3. Of these, 222/1351 (16.4%) were considered eligible for focal therapy based on the proposed criteria. Eligibility group mean age and PSA at time of biopsy was 66.0 years (SD 7.8) and 8.55 ng/mL; (SD 7.6), respectively. Fusion biopsy was performed for elevated PSA in 175/222 (78.8%), monitoring on active surveillance in 112/222 (50.5%), and prior negative biopsy in 51/222 (30.0%).  ROI biopsy pathology revealed that 167/222 (75.2%) had single ROI GG2 disease, and 55/222 (24.8%) had single ROI GG3.  62/222 (27.9%) had GG1 disease detected elsewhere, with 4/62 (6.4%) found in a separate ROI and 59/62 (95.2%) in a systematic core.

Conclusion:

A small but specific group of men in this cohort (16.4%) who underwent MRI fusion prostate biopsy harbored intermediate risk prostate cancer eligible for focal therapy ablation based on our definition. Further post-prostatectomy mapping studies are needed to best define ablation templates in this intermediate risk population.

Funding: N/A