Purpose
Our aim was to evaluate whether transperineal (TP) MRI-targeted prostate biopsy (TBx) may improve the detection of clinically significant prostate cancer (csPCa), defined as International Society of Urological Pathology 2, in comparison to transrectal (TR) TBx.
Materials and Methods
A multicenter retrospective cohort study comprising patients who underwent MRIguided prostate biopsy was conducted. To address possible benefits of TP-TBx in the detection of prostate cancer (PCa) and csPCa, a cohort of patients undergoing TP-TBx were compared to patients undergoing TRTBx. Multivariable logistic regression analyses were performed to assess predictors of PCa and csPCa detection.
Results
Overall, 1,936 and 3,305 patients who underwent TR-TBx vs TP-TBx at 10 referral centers were enrolled. The rate of PCa and csPCa diagnosed was higher for TP-TBx vs TR-TBx (64.0% vs 50%, p <0.01 and 49% vs 35%, p <0.01). At multivariable analysis adjusted for age, biopsy naıve/repeated biopsy, cT stage, Prostate Imaginge Reporting and Data System, prostate volume, PSA, and number of biopsy cores targeted, TP-TBx was an independent predictor of PCa (odds ratio [OR] 1.37, 95% CI 1.08e1.72) and csPCa (1.19, 95% CI 1.12e1.50). When considering the approach according to the site of the index lesion, TP-TBx had a significantly higher likelihood than TR-TBx to detect csPCa in the apex (OR 4.81, 95% CI 1.03e6.27), transition/central zone (OR 2.67, 95% CI 1.42e5.00), and anterior zone (OR 5.62, 95% CI 1.74e8.13).
Conclusions
The use of TP-TBx allows a better cancer grade definition and PCa risk assessment. This has important implication in the decision-making process and in patient counseling for further therapies.
The diagnostic pathway for prostate cancer (PCa) has dramatically changed in the past decade. The incorporation of risk calculators, MRI, and targeted biopsies have impacted both the biopsy indication, as well as the biopsy strategy (systematic cores, targeted cores, perilesional cores, combinations). These improvements have led to less negative biopsies, less indolent cancers found, and higher detection rates of significant cancers.
The approach (transperineal (TP) versus transrectal (TR)) has also received much attention recently. TP biopsy is not new, but its advantages regarding the lower infection rates have renewed the interest in this technique. TP biopsy approach has now been recommended by the EAU guidelines as the preferred modality.(1) Besides infectious side effects, the different biopsy approaches have an impact on other aspects as well, such as cancer detection. This is an important outcome that may have to be taken into account when deciding on the most appropriate technique.
Zattoni et al. performed a multicentre (10 centres) retrospective cohort study on cancer detection rates comparing results between the TR vs TP biopsy approaches.(2) All patients underwent MRI-guided prostate biopsy. Rates of significant PCa (ISUP grade ³2) were compared between almost 2000 men after TR and 3300 men after TP. The rate of significant PCa diagnosed was higher for TP-TBx vs TR-TBx (49% vs 35%, p <0.01). While the rate of previous negative biopsies was comparable between groups, other patient and biopsy parameters differed significantly. After correcting for these variables, biopsy approach still remained a significant predictor of finding ISUP grade ³2 cancer. Especially for MRI lesions in apical, transition, and anterior zones, TP proved beneficial.
Of note, all men in this analysis had a positive MRI scan. It is unknown if the found advantage of TP biopsy would also be applicable to the systematic strategy in men without MRI abnormalities. However, the indication to do a biopsy in these men may be decreasing. Also, the study group consists of somewhat heterogeneous participants, in whom different fusion techniques for targeting were used.
Different explanations have been suggested for the higher cancer detection rate in TP biopsies versus TR, including: easier access to the apical and anterior zone, biopsy core direction parallel to most common largest tumour dimension, improved sampling of the peripheral zone, and technically more straightforward 3D orientation during the procedure.
Many aspects are different between TP and TR biopsy approaches and should be taken into account. The most important may be side effects and cancer detection, but other factors such as costs and logistics may also play a role. With the infection rates in favour of TP biopsy, a non-inferior cancer detection would be sufficient to favour this approach over TR. If the TP technique also should yield a higher significant cancer detection, as suggested by Zattoni et al, the debate on the preferred biopsy approach may be closed forever. A randomised study design would be the most ideal setting to address this question.
We are in the middle of important changes in the diagnostic pathway, with a dramatic impact on millions of men with the suspicion of PCa. Further developments may include optimisation of predictive MRI parameters, incorporation of new imaging techniques, individualisation of biopsy strategies, and including follow-up over time to improve biopsy decisions. A freehand TP, cognitive-fusion, targeted-only biopsy, under local anaesthesia, is an easily accessible technique, exploiting all advantages of the recent improvements.
References