Research in context
Evidence before this study
We searched PubMed for publications in English or French using the search terms “prostate cancer”, “MRI”, “prostate biopsy”, “systematic biopsy”, and “targeted biopsy”. When MRI-FIRST was designed in 2013, no prospective randomised trials had compared systematic and targeted biopsy in biopsy-naive patients. At least three systematic reviews, published in 2014 and 2015, suggested that targeted biopsy detected more clinically significant prostate cancer than did systematic biopsy. However, one of these reviews showed that the improvement in detection of clinically significant prostate cancer because of targeted biopsy was substantial in patients with a history of negative biopsy, but was only marginal in biopsy-naive men. At least five prospective single-centre randomised trials, published between 2015 and 2017, gave contradictory results regarding whether targeted biopsy could improve detection of clinically significant prostate cancer in biopsy-naive patients. The prospective multicentre PROMIS study, published in 2017, assessed multiparametric MRI and systematic biopsy against template prostate mapping biopsy in biopsy-naive men and showed that multiparametric MRI was significantly more sensitive than systematic biopsy in detecting clinically significant prostate cancer, defined as International Society of Urocological pathology (ISUP) grade group 3 or higher tumours, or tumours with maximum cancer core length of at least 6 mm. The prospective multicentre PRECISION study, published in 2018, randomly assigned biopsy-naive men to either systematic biopsy without multiparametric MRI or to pre-biopsy multiparametric MRI with no biopsy if the multiparametric MRI was negative, and only to targeted biopsy if the multiparametric MRI was positive. The detection rate of ISUP grade group 2 or higher tumours was significantly higher in men assigned to multiparametric MRI and targeted biopsy than in those assigned to systematic biopsy. By contrast, the detection of clinically insignificant tumours (ISUP grade group 1 tumours) was significantly higher in patients assigned to systematic biopsy.
Added value of this study
Rather than randomly assigning patients to either systematic or targeted biopsy, we chose to do both biopsy techniques in the same biopsy-naive men. This approach allowed us to separately investigate the added value of systematic and targeted biopsy by analysing discordant pairs. The results of this study nuance the results of the PRECISION trial. Indeed, we found that both systematic and targeted biopsy had substantial added value in detecting ISUP grade group 2 or higher tumours since a third of these were detected by only one biopsy technique. The added value of systematic biopsy was marginal only for the detection of ISUP grade group 3 or higher tumours. Similar to the PRECISION trial, targeted biopsy in MRI-FIRST detected significantly fewer low-volume, low-grade tumours than did systematic biopsy.
Implications of all the available evidence
Findings from both the MRI-FIRST and PRECISION trials suggest that multiparametric MRI could be safely used as a triage test for the detection of ISUP grade group 3 or higher cancers, and that targeted biopsy has added value in the detection of ISUP grade group 2 or higher cancers. The use of targeted biopsy alone could decrease the detection of non-significant prostate cancer, but the added value of systematic biopsy could still be substantial for the detection of ISUP grade group 2 or higher cancers, which might be optimised when both approaches are combined. Further research is needed to assess the influence of the number of targeted cores on targeted biopsy accuracy, which was lower (on average) in MRI-FIRST than in the PRECISION trial.