Combination of multiparametric magnetic resonance imaging and transperineal template-guided mapping prostate biopsy to determine potential candidates for focal therapy

Abstract

Background: We assessed the ability of the combination of multiparametric magnetic resonance imaging (mpMRI) and transperineal template-guided mapping biopsy (TTMB) to determine the eligibility for focal therapy (FT) (hemiablation) in men and compared it with that of histology from radical prostatectomy (RP) specimens.

Materials and methods: In this study, 120 men who underwent mpMRI, TTMB, and RP in a single tertiary center from May 2017 to June 2021 were analyzed. The criteria of hemiablation eligibility were unilateral low-to intermediate-risk prostate cancer (limited to a maximum of International Society of Urological Pathology (ISUP) grade group 3 and prostate-specific antigen (PSA) <20 ng/mL) and clinical stage ≤T2. Evidence of non-organ-confined disease or contralateral Prostate Imaging Reporting and Data System (PI-RADS) v2 score ≥4 on mpMRI was classified as ineligible for hemiablation. Clinically significant cancer at RP was defined as any of the following: (1) ISUP grade group 1 with tumor volume ≥1.3 mL; (2) ISUP grade group ≥2; or (3) the presence of advanced stage (≥pT3).

Results: Of the 120 men, data of 52 men who met the selection criteria for hemiablation were compared with final RP findings. Of these 52 men, 42 (80.7%) could be considered suitable for hemiablation on RP. The sensitivity, specificity, and accuracy of mpMRI and TTMB in predicting FT eligibility were 80.7%, 85.1%, and 82.5%, respectively. The rate of undetected contralateral significant cancer was 10 (19.2%) on mpMRI and TTMB. Six had bilateral significant cancer and four had small volumes of ISUP grade group ≥2.

Conclusions: The combination of mpMRI and TTMB substantially improves the prediction of potential candidates for hemiablation based on consensus recommendations. Improved selection criteria and further investigative tools are required to improve patient selection for hemiablation.

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

Fig. 1

Flow chart to identify the number of potential candidates for focal therapy. All 120 patients undergoing mpMRI, TTMB, and RP were screened for hemiablation eligibility, of whom 52 had unilateral prostate cancer in the combination of mpMRI and TTMB. Forty-one were considered potential candidates for hemiablation according to the criteria of ISUP grade group ≤2 and PSA <15 ng/mL and 11 met the screening criteria according to extended criteria of ISUP grade group 3 or PSA 15–20 ng/mL. ISUP, International Society of Urological Pathology; mpMRI, multiparametric magnetic resonance imaging; PI-RADS, Prostate Imaging Reporting and Data System; PSA, prostate-specific antigen; RP, radical prostatectomy; TTMB, transperineal template-guided mapping biopsy.

Fig. 2

Flow diagram of patients considered suitable for focal therapy based on mpMRI and TTMB (according to the criteria of ISUP grade group ≤2 and PSA <15 ng/mL). ISUP, International Society of Urological Pathology; PSA, prostate-specific antigen; RP, radical prostatectomy; mpMRI, multiparametric magnetic resonance imaging; TTMB, transperineal template-guided mapping biopsy.

Fig. 3

Flow diagram of patients considered suitable for focal therapy based on mpMRI and TTMB (according to the extended criteria of ISUP grade group 3 or PSA 15–20 ng/mL). ISUP, International Society of Urological Pathology; PSA, prostate-specific antigen; RP, radical prostatectomy; mpMRI, multiparametric magnetic resonance imaging; TTMB, transperineal template-guided mapping biopsy.