Introduction

There is growing interest on the using of prostate mpMRI for performing targeted biopsies. However, lack of consensus exists whether it is mandatory to perform concomitant systematic biopsies. The aim of this study was to assess the predictors of clinical significant prostate cancer (csPCa) outside the mpMRI detected index lesion (IL) and to assess whether MRI parameters may predict csPCa outside IL

Methods

244 patients underwent mpMRI of the prostate with subsequent biopsy between 2013 and 2016 at a single tertiary referral centre. A 1.5 T mpMRI study using an endorectal coil was performed in all patients. Lesions suggesting of significant PCa visualized on mpMRI, defined as PI-RADS v.2 ≥3, were targeted with cognitive or fusion approach. Furthermore each patient was submitted to standard random biopsy during the same session. csPCa was defined as Gleason Score ≥7. Multivariable logistic regression analysis (MVA) was performed to assess the predictors of csPCa outside the IL. Covariates consisted of age at biopsy, PSA, prostate volume, digital rectal examination (negative vs. positive), PI-RADS (3 vs. >3), IL volume, number of ILs, number of random cores and previous biopsy (biopsy naive vs. previous negative biopsy vs. previous positive biopsy)

Results

Overall, 46 and 54% of patients were previous biopsied and biopsy naive, respectively. Median PSA, prostate volume, number of random cores, number of ILs, IL volume were 7 ng/ml, 47 cc, 12, 1, 0.70 cc, respectively. The overall detection rate of csPCa outside the IL was 34%. When patients were stratified according to the targeted biopsy results, the detection rate of csPCa outside the IL was 10 and 30% in men with a negative and positive targeted biopsy, respectively. At MVA age (OR: 1.07; p=0.01), PSA (OR: 1.12; p=0.01), prostate volume (OR: 0.98; p=0.02), positive digital rectal examination (OR 3.7; p<0.01) and previous negative biopsy (OR 0.31; p=0.01) were independent predictors of the presence of overall csPCa outside the IL (AUC: 65%). Conversely, PI-RADS, IL volume, number of ILs detected at mpMRI were not associated with overall detection of csPCa outside the IL (all p≥0.1)

Conclusions

mpMRI missed csPCa outside the IL in approximately a third of men. Despite the presence of clinical predictors, neither patient characteristics nor mpMRI data are able to reliably select patients candidate for targeted biopsy alone (AUC: 65%). Therefore, based on our data, systematic biopsies should be always performed in conjunction with targeted biopsy in men with suspected csPCa at mpMRI

Funding

none