# Omission of contralateral biopsies in unilateral MRI‐suspicious prostate cancer has minimal impact on clinical risk assessment

## TL;DR

Omitting contralateral biopsies in unilateral prostate cancer cases has little effect on risk assessment, but adding ipsilateral biopsies improves detection of higher-grade cancer.

## Contribution

This study quantifies the clinical impact of omitting contralateral biopsies in unilateral MRI-suspicious prostate cancer cases.

## Key findings

- Omitting contralateral biopsies changed ISUP grading in 7.4% of patients and risk classification in 2.6%.
- Ipsilateral systematic biopsies increased sensitivity for detecting ISUP ≥3 cancer from 82% to 98%.
- Only 1.1% of patients had clinically significant cancer detected solely in contralateral cores.

## Abstract

MRI‐targeted biopsies (TBx) combined with systematic biopsies (SBx) have traditionally been recommended for patients with unilateral MRI‐suspicious prostate cancer (PCa) lesions. Recent European Association of Urology (EAU) guidelines propose that, in cases with a solitary lesion, TBx with perilesional sampling may suffice, potentially omitting contralateral SBx. The clinical impact of this omission remains uncertain. This study evaluates how omitting contralateral SBx affects pathological grading, EAU risk classification, and estimated lymph node involvement (LNI).

We conducted a retrospective cohort study (2016–2024) including 190 biopsy‐naïve men diagnosed with PCa via TBx and bilateral SBx for a single, unilateral MRI‐visible lesion. Outcomes were re‐evaluated using only TBx and ipsilateral SBx, simulating omission of contralateral SBx. Changes in ISUP grade, EAU risk group, and LNI probability using the Briganti 2019, Amsterdam–Brisbane–Sydney (ABS), and Memorial Sloan Kettering Cancer Center (MSKCC) nomograms were assessed. Furthermore, we compared cancer detection rates for TBx alone versus TBx plus ipsilateral SBx.

ISUP grading changed in 14 of 190 patients (7.4%) when contralateral SBx was omitted; two patients (1.1%) had clinically significant PCa (ISUP 2) detected solely in contralateral cores. In seven patients (3.7%), only ISUP 1 cancer was found in contralateral SBx, meaning no diagnosis would have been made without those cores. EAU risk classification changed in five patients (2.6%). LNI estimates were affected minimally: One patient (0.5%) dropped below the Briganti 7% threshold, and one patient (1.2%) no longer met the 8% ABS threshold. The MSKCC model showed a statistically significant 8% increase in patients above the 7% ePLND threshold when contralateral SBx was omitted (p = 0.0023). Ipsilateral SBx substantially improved detection of higher‐grade disease: sensitivity for ISUP ≥3 increased from 82% with TBx alone to 98% when combined with ipsilateral SBx.

Omitting contralateral SBx in patients with unilateral MRI lesions had limited effect on grading, risk classification, and LNI estimates. However, ipsilateral SBx adds significant diagnostic value compared with TBx alone and should be retained. These findings support a more targeted diagnostic approach in patients with a unilateral lesion on MRI in a primary diagnostic setting.