To assess the diagnostic yield of consecutive transperineal targeted biopsy (TBx) of mpMRI index-(IL) and secondary lesion (SL) and additive systematic biopsy (SBx) in patients who received combined TBx+SBx of prostate.

Of 1,467 patients with TBx+SBx, analyses were restricted to 571 patients with IL+SL, PI-RADS≥3. IL was defined as having the greatest PI-RADS score and/or lesion volume as opposed to SL. We retrospectively compared clinically significant prostate cancer (csPCa) rates (i.e.Gleason Grade Group≥2) between IL+SL and IL+SL+SBx. Subgroup analyses in men with ipsilateral IL+SL focused on contralateral SBx. Multivariable logistic regression analyses (MVA) to predict any csPCa included age, previous biopsies, PSA density, respective IL/SL-volumes, -side relation, -PI-RADS strata and number of TBx and SBx cores.

CsPCa rates for IL+SL vs. IL+SL+SBx were 38 vs. 42% (p=0.2) at expense of significantly higher median number of biopsy cores (9 vs.25; p<0.001). In the subgroup with ipsilateral IL+SL (n=236), contralateral SBx detected csPCa in 17%. In the narrower subgroup with ipsilateral IL+SL (n=131) without any csPCa, contralateral SBx detected csPCa in 3.8%. MVA confirmed contralateral SBx as independent predictor, but performed similarly without SBx information (AUC 87.1 vs.86.6%).

TBx of SL should be included in TBx protocols due to added diagnostic information. However, for TBx of IL+SL additional SBx is of limited informative value in terms of overall csPCa detection. However, when IL+SL are ipsilateral, contralateral SBx should be recommended for purpose of prostate lobe information. Our results indicate great potential to reduce SBx cores and associated potential morbidity and warrant prospective evaluation.