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New England Section of the American Urological Association

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Unilateral ROI on MRI, Do We Really Need to Sample the Contralateral Gland?
Esther L. Finney, MD1, Nathanaelle O. Ibeziako, BS2, Alireza Moinzadeh, MD, MBA1, Daneil Kuftinec, MD1, Manuel Merino, MD1, William Faust, MD1.
1Lahey Hospital and Medical Center, Burlington, MA, USA, 2Tufts University School of Medicine, Boston, MA, USA.

BACKGROUND: Debate exists regarding the added utility of performing systematic biopsy at the time of MRI targeted prostate biopsy. Existing literature suggests that a number of patients with clinically-significant prostate cancer (csPCa), defined as Gleason Grade Group 2 or above, would be missed if only targeted biopsy is performed. Whether this represents the sampling of discrete MRI invisible lesions, or is merely a field effect around the target lesion, remains unknown. We aim to assess the cancer detection rate (CDR) and clinically-significant cancer detection rate (csCDR) in the contralateral gland for patients with unilateral lesions on MRI undergoing targeted and concomitant 12-core systematic prostate biopsy.
METHODS: We performed a retrospective chart review of all patients who have undergone TRUS-guided fusion prostate biopsy at a single institution from 2015-2020. All patients had been found to have at least one PIRADS-3, -4, or -5 lesion on MRI prior to undergoing subsequent UroNav® targeted fusion biopsy. Number of targeted cores obtained were at the discretion of the urologist performing the biopsy. A standard 12-core systematic biopsy was performed simultaneously on all patients. Biopsies were performed by two senior urologists and cores evaluated by a dedicated genitourinary pathologist. Lesions were retrospectively categorized as right or left and anterior or posterior.
RESULTS: Of 736 patients identified, 514 (74%) had unilateral lesions on MRI. The indication for MRI was cancer screening in 367/514 (71%) patients and active surveillance for 141/514 (27%). A median of three targeted cores were obtained per lesion. The overall CDR in the contralateral gland was 15% for PIRADS-3, 21% for PIRADS-4, and 29% for PIRADS-5 lesions. The csCDR in the contralateral gland was 5% for PIRADS-3, 9% for PIRADS-4, and 12% for PIRADS-5. Only one percent of patients (7/514) had clinically-significant cancer detected in the contralateral gland only (i.e not detected on targeted or ipsilateral cores). For patients with unilateral PIRADS-5 lesions, there was no added detection of csPCa from biopsying the contralateral gland.
CONCLUSIONS: For patients with unilateral lesions on MRI, there was a 1% detection rate of csPCa in the contralateral gland only. The added yield of systematic biopsy of the contralateral gland for patients with unilateral lesions undergoing MRI-TRUS fusion prostate biopsy may be extremely low.

Contralateral gland cancer detection in patients with unilateral lesions (N=514)
PIRADS-324/156 (25%)8/156 (5%)
PIRADS-451/242 (21%)22/242 (9%)
PIRADS-533/115 (29%)13/115 (11%)
All108/514 (21%)43/514 (8%)

Detection of prostate cancer only within the contralateral gland (N=514)
PIRADS-310/156 (6%)1/156 (1%)
PIRADS-49/243 (4%)6/243 (2%)
PIRADS-51/115 (1%)0/115
All20/514 (4%)7/514 (1%)

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