Editorial Comment to: Use of High-resolution Micro-ultrasound to Predict Extraprostatic Extension of Prostate Cancer Prior to Surgery: A Prospective Single-institutional Study

Citation: Fasulo V, Paciotti M, Buffi NM, Lughezzani G (2022) Editorial Comment to: Use of High-resolution Micro-ultrasound to Predict Extraprostatic Extension of Prostate Cancer Prior to Surgery: A Prospective Single-institutional Study, 21st Century Pathology, Volume 2 (6): 135

Abstract

Extra prostatic extension (EPE) is an important risk factor for the recurrence or progression of prostate cancer (PCa) after radical prostatectomy. To maximize oncological and functional outcomes, a tailored nerve-sparing approach should be offered to all patients, especially in those with high-risk disease and no signs of EPE at preoperative evaluation. The role of imaging for the preoperative risk-stratification of EPE in PCa candidates is under investigation. In this setting, micro-US may play an important part in primary staging, being a ready-to-use instrument easily adoptable by urologists.

Keywords:

Micro-ultrasound; Prostate cancer; Extra prostatic extension; Local Staging

Introduction

The improvement in surgical techniques in robotic radical prostatectomy (RARP) ensures tailored nerve-sparing approaches adapted to patient characteristics. Being oncological safety the primary objective, a perfect merge between optimal oncological and functional outcomes is what urologists in a high-volume center should always aim to guarantee to their patients [1,2]. To pursue this goal, a precise preoperative assessment of the clinical stage of prostate cancer (PCa) is essential.

Extra prostatic extension (EPE), is one of the main risk factors for relapse and progression after surgery [3,4]. Currently, multiparametric magnetic resonance imaging (mpMRI) is the most used tool for EPE assessment, as well as the only one able to evaluate its localization, providing information regarding its side and location [5].

European Association of Urology guidelines suggest using mpMRI for staging any risk group. However, no specific mention is made on how to assess EPE or how these results may guide a nerve-sparing procedure. Combination of clinical parameters, such as the International Society of Urological Pathology (ISUP) grade group, and mpMRI-derived parameters may be helpful, but the lack of standardization makes the routine use of these parameters quite cumbersome [6]. This lack has prompted the search for novel tools for primary staging. For instance, 29 MHz ExactVu? (Exact Imaging, Markham, Canada) high-resolution micro-ultrasound (micro-US) system have been recently recommended and early results are absolutely encouraging [7].

Discussion

The lack of standardization in the evaluation of EPE with mpMRI was addressed by Mehralivand S, et al. (2008) with the introduction of a grading system [8]. In their study on 553 patients, they selected the three most accurate mpMRI derived features to outline three grades of EPE risk: ?curvilinear contact length? or ?capsular bulge/irregularity? (Grade 1), ?curvilinear contact length associated with capsular bulge/irregularity? (Grade 2) and then with the highest risk of EPE ?frank breach of prostatic capsule or invasion of adjacent structures? (Grade 3). This grading system represents a nice effort to standardize mpMRI findings. However, it is not systematically used and routinely reported by most radiologists. In addition to this, we must consider that mpMRI needs a long learning curve, so in the absence of an experienced and dedicated radiologist, many mpMRIs are often uninformative or may provide unreliable results.

MicroUS for prostate evaluation has been largely studied and it resulted to be as accurate as mpMRI. Comparative studies by Lughezzani G, et al. (2019) showed optimal performance in diagnosing clinically significant PCa (csPCa) and even greater performance in association with mpMRI [9,10].

The advantages of the microUS consist of being an easily accessible and time-saving tool for urologists and its central role in three different clinical scenarios of prostate evaluation: first, in a screening context, it may help to rule out candidates for biopsy; second, it may provide an optimal real-time guidance during targeted biopsies; third, it may help to tailor a nerve-sparing approach, stratifying the risk of EPE in the preoperative setting.

Moreover, for primary staging, microUS can be easily performed the day prior to surgery or even in the operating room few minutes before surgery, providing readily available information to the surgeon.

The feasibility of MicroUS in primary staging was found by Regis F, et al. (2020) and was then validated in an enlarged cohort by Fasulo V, et al. (2022) [7,11]. This study demonstrated that the addition of one to four micro-US predictors (e.g., capsular bulging, visible breach of the prostate capsule, (?visible ECE?), presence of a hypoechoic halo and obliteration of the prostatic-seminal vesicle angle) to clinical variables results in a significant increase in the accuracy of EPE assessment, compared to clinical variables alone. In this study at a multivariable logistic regression model demonstrated an area under the ROC curve of 87.6% for detection of EPE, of a model including clinical and microUS predictors vs 82.0% of the clinical model alone. Visible ECE at microUS resulted to be the best predictor with a sensitivity of 72%, specificity of 88 %, negative predictive value of 80% and a positive predictive value of 83%.

Nevertheless, as it happens for mpMRI, microUS, needs a learning curve for correct image interpretation. Additionally, further larger-scale evidences and a head-to-head comparison with mpMRI is warranted to further promote the use of this promising technology in clinical practice.

Conclusion

The pursue of a tailored nerve-sparing approach in RARP candidates represent an important task for practicing urologists. MicroUs may represent a viable tool for urologists and can play a substantial role in primary local staging, especially in those patients harboring an intermediate to high-risk PCa.

Author Contribution

Conceptualization: VF, MP, NMB, GL. Data curation: VF, MP, NMB, GL. Formal analysis: VF, MP. Funding acquisition: NMB, GL. Methodology: VF, MP, NMB, GL. Project administration: VF, MP, NMB, GL. Visualization: VF, MP, NMB, GL. Writing ? original draft: VF. Writing ? review & editing: VF, MP, NMB, GL

Conflict of Interest

No potential conflict of interest relevant to this article was reported.