Tailoring biopsy strategy in the MRI-fusion prostate biopsy era: systematic, targeted or neither?

Background Magnetic resonance imaging (MRI) followed by targeted biopsy (TBx) is utilized for prostate cancer (PCa) detection. However, the value of adding systematic biopsies (SBx) to targeted biopsy procedures (combined biopsy; CBx) in men with suspicious MRI findings has not been determined. Methods We analysed biopsy outcomes in 429 men with MRI lesions in the prospective multicenter STHLM3MRI pilot study, planned for prostate biopsy. Participants underwent 1.5T biparametric MRI without contrast enhancement, reported according to the PI-RADS v2, and with TBx plus SBx if the MRI lesion score was >= 3. The endpoints were clinically nonsignificant (nsPCa) and clinically significant PCa (csPCa), defined as ISUP grade groups 1 and >= 2, respectively. Results The median age was 65 years (59-70), and the median PSA 6.0 ng/ml (4.1-9.0). The detection rates of csPCa when using TBx or SBx combined were 18%, 46%, and 85% in men with PIRADS scores of 3 (n = 195), 4 (n = 121), and 5 (n = 113), respectively. This combined strategy detected csPCa in more men than TBx alone (43.6% vs 39.2%, p < 0.02), with similar detection of nsPCa (19.3% vs 17.7%, p = 0.2). In men with equivocal lesions (PI-RADS 3), the detection rates for csPCa were similar for the combined strategy and for TBx alone (17.9% and 15.4%, p = 0.06). However, there was an increase in the detection of nsPCa when using the combined strategy (21.0% vs 15.4%, p < 0.02). Men with equivocal lesions and a PSA density < 0.1 ng/ml(2) or a Stockholm 3 test < 0.11 had a low risk of harboring csPCa. Conclusions Supplementing targeted with systematic biopsies enhances clinically significant cancer detection. However, in men with equivocal lesions, this combination has potential for detecting nonsignificant disease. A subgroup of men with equivocal MRI findings may be identified as having a low risk for significant cancer and spared unnecessary biopsies.