Impact of omitting contralateral systematic biopsy on clinically significant upgrading at radical prostatectomy: a retrospective paired-design study.

PURPOSE: Whether contralateral systematic biopsy (SB) can be safely omitted when combined with MRI-targeted biopsy (TB) remains debated. This study compared the pathological concordance of TB plus ipsilateral SB (TBI) versus TB plus bilateral SB (TBB) against radical prostatectomy (RP) whole-mount pathology in a Chinese cohort. METHODS: In this paired-design study, 246 Chinese men who underwent transperineal MRI-TRUS fusion combined biopsy followed by RP (2017-2024) were included. Five biopsy strategies (TBB, TBI, SB-only, TB-only, TB+contralateral SB) were retrospectively reconstructed from the same procedure. The major outcomes were clinically significant upgrade (CTC-upgrade: biopsy Grade Group [GG] ≤ 1 → RP GG ≥ 2, including GG0) and any-upgrade (biopsy GG < RP GG). Minor outcomes included exact concordance, any downgrade, high-risk upgrade, and clinically significant downgrade. Paired comparisons used the McNemar test with Bonferroni correction. RESULTS: CTC-upgrade rates were 13.8% for TBB and 15.0% for TBI (McNemar p = 0.25), with 3 discordant pairs (absolute difference 1.2% [95% CI 0.3-3.5%]). A post-hoc non-inferiority analysis confirmed adequate study power of 0.94 (non-inferiority margin - 5%). TBI showed modestly higher any-upgrade (33.7% vs. 30.9%, p = 0.016). No significant differences were observed across minor outcomes. SB-only, TB-only, and TB+contralateral SB had significantly higher CTC-upgrade rates (24.8%, 24.4%, 21.5%; all p < 0.001 vs. TBB). No subgroup showed a significant CTC-upgrade difference. CONCLUSION: TBI demonstrated broadly similar pathological grade accuracy to TBB. The incremental contribution of contralateral systematic biopsy to clinically significant upgrading was small.