The role of prostate MRI in clinical staging of prostate cancer before radical prostatectomy

Abstract

Objective: Transrectal ultrasonography (TRUS) guided biopsy is the main method used for the diagnosis of prostate cancer. However, it may be challenging to determine the extraprostatic extension (EPE) and seminal vesicle invasion (SVI) based solely on pathology alone. Newer imaging techniques may have the potential to improve differentiation between localized and locally advanced diseases. The objective of this study is to evaluate the accuracy of mpMRI in the determination of extraprostatic extension EPE and SVI of prostate cancer with regard to the final pathology, and to predict lymph node (LN) involvement.

Materials and Methods: This retrospective study evaluated the data from the medical records of male patients with prostate cancer who underwent preoperative mpMRI (at either 3.0 Tesla or 1.5 Tesla) followed by either robotic-assisted laparoscopic radical prostatectomy or laparoscopic radical prostatectomy, between January 2017 and October 2022. The area under the receiver operating characteristic curve (AUC) value was used in multivariable analysis to compare the performance of mpMRI and clinical data (prostate-specific antigen, ISUP category) in predicting pathologic EPE or SVI.

Results: The study looked at the data pertinent to 98 men with prostate cancer who underwent an MRI scan (mpMRI) before surgery (radical prostatectomy). The average age was 67 and the average PSA level was 19.81 ng/ml. The final pathology was reviewed to see if the cancer had spread outside the prostate (extracapsular extension, EPE) or into the SVI. These are signs of a more advanced cancer. At radical prostatectomy a total of 56 out of 98 (57.14%) patients had pathologic EPE, and 22 out of 98 (22.45%) patients had pathologic SVI. To determine the relationship between mpMRI staging and pathological staging, univariate analysis was conducted. EPE and SVI were combined to characterize them as locally progressed diseases and to enhance effective prediction. The data indicated 50.88%, 95.12%, 93.55%, and 58.21% of cases, for specificity, sensitivity, positive predictive value, and negative predictive value respectively. In summary, the mpMRI has a strong ability to inform the treatment of locally advanced disease due to its ability to determine the EPE and SVI on the final pathology. The limited level of sensitivity is currently limiting and warrants further research.

Conclusion: This study suggests that mpMRI can be a valuable tool for the identification of prostate cancer in patients who are unlikely to have advanced stages of the disease (EPE or SVI). However, due to its limited sensitivity, it may limit the diagnosis of cases of advanced cancer. Therefore, a negative mpMRI result should not completely rule out the possibility of advanced disease, and additional evaluation may be necessary.