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MRI changes paradigm for prostate cancer detection

By Prof. Igor Tsaur (on behalf of UROONCO PCa editorial board

Growing body of evidence favors increasing routine utilization of multiparametric magnetic resonance imaging (mpMRI) in the diagnostic work-up of prostate cancer (PCa). In males with a clinical suspicion of PCa, EAU guidelines advocate performing mpMRI as one of the options for risk stratification, and in case of a positive finding (PI-RADS lesion ≥ 3) a combined targeted and systematic prostate biopsy. In patients with a prior negative biopsy, mpMRI and, in case of positive lesions, only targeted biopsies are recommended. 

Still, there are considerable discrepancies in trial findings concerning advantages of MR-targeted over systematic approach as well as their added value for combined strategy. The recently published prospective multicenter PRECISION trial by Kasivisvanathan et al. compared MRI-guided approach including MRI-targeted biopsies (without concomitant systematic biopsies) in case of suspicious lesions to a standard systematic ultrasound-guided biopsy in 500 biopsy-naïve men with a clinical PCa suspicion. MRI-tailored strategy outperformed systematic approach by detecting more clinically significant and fewer insignificant tumors, reducing the number of men undergoing biopsy and participant-reported adverse events at 30 days. 

Interestingly, a contemporary retrospective unicenter analysis of both biopsy-naïve and patients with prior biopsies undergoing combined targeted and systematic biopsies by Preisser et al. yielded comparable detection rate of significant PCa between targeted and systematic biopsies in 141 biopsy-naïve males, both being considerably higher than in the PRECISION study. This might be at least in part explained by the operator bias, since combined targeted and systematic biopsy were both performed by the same operator in the same patient unblinded to the mpMRI results. Of note, combined approach provided only a slight increase in the detection rate of significant PCa in biopsy-naïve men and those with one previous biopsy at most. 

This is in clear contradiction to the prospective multicenter paired MRI-FIRST trial recently published by Rouvière and co-workers, in which the operator performing systematic biopsy was masked to mpMRI results and another one carried out targeted biopsies. While detection rate of significant PCa was similar with targeted and systematic biopsies in 275 biopsy-naïve males, combined biopsy yielded a 3-fold higher number. 

Another prospective trial with similar design by Leest et al. investigated in-bore MRI-guided biopsy and systematic biopsy in the same patient in 626 biopsy-naïve males, whereas both procedures were performed by different operators and blinding of the urologist performing systematic biopsy to imaging results. Both approaches were accompanied by the same detection rate of clinically significant PCa, whereas a lower rate of insignificant disease was demonstrated for MRI-guided strategy. Of note, in men with unsuspicious mpMRI, systematic biopsy led to identification of significant PCa in 4% and insignificant disease in 20%. In those with positive mpMRI, combined biopsy resulted in detection of additional 7% significant tumors. 

Taken together, further research is warranted to answer the question whether significant PCa detection benefit of adding systematic biopsies to MRI-targeted ones overweighs the risk of adverse events and overdetection of insignificant PCa.