Combination of multiparametric magnetic resonance imaging and transrectal ultrasound-guided prostate biopsies is not enough for identifying patients eligible for hemiablative focal therapy for prostate cancer

Abstract

Purpose: To evaluate focal therapy (hemiablation) eligibility in men undergoing prostate biopsy and multiparametric magnetic resonance imaging (mpMRI) with reference to histopathology from radical prostatectomy (RP) specimens.

Methods: Subjects were selected among 810 men who underwent prostate biopsy, mpMRI, and RP from January 2016 to December 2017. Hemiablation eligibility criteria were biopsy-proven unilateral cancer, prostate-specific antigen ≤ 15 ng/ml, and Gleason score (GS) ≤ 3 + 4. Evidence of non-organ-confined disease or Prostate Imaging Reporting and Data System score ≥ 4 on the contralateral lobe on mpMRI was classified as ineligible for hemiablation. Of the 810, data for 185 who met the screening criteria were compared to final pathology findings. Significant cancer at RP was defined as any of the following: (1) GS 6 with tumor volume ≥ 0.5 ml; (2) GS ≥ 3 + 4; or (3) the presence of advanced stage (≥ pT3).

Results: Among the 185 candidates for hemiablation, 62 (33.5%) had unilateral cancer on final RP histopathology. Among the 123 bilateral cancers, 50 (27%) were organ confined and had GS ≤ 3 + 4 = 7 and bilateral multifocal tumor in which the index tumor was confined to one lobe and the secondary tumor in the contralateral lobe had tumor volume < 0.5 ml and GS ≤ 6. A total of 112 (60.5%) patients in this series were considered suitable for hemiablation. Significant cancer on biopsy and mpMRI-negative lobes were found in 72 (38.9%) of 185 lobes, including 1 (0.5%) with advanced stage.

Conclusions: The combination of standard prostate biopsy and mpMRI did not accurately identify lobes that could be considered as non-treated regions.

Keywords: Focal therapy; Hemiablation; Magnetic resonance imaging; Prostate biopsy; Prostate cancer.