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ESOU 2019

ESOU 2019: Definition and Interpretation of PI-RADS 3 on mpMRI: Counseling Patients from the Urologist’s and Radiologist’s Perspective

Prague, Czech Republic (UroToday.com) With the widespread utilization of prostate multiparametric MRI (mpMRI), there is debate regarding the subsequent steps in management for patients with PI-RADs 3 prostate lesions. To assess this diagnostic conundrum, Dr. Radtke, a urologist from Heidelberg, Germany, and Dr. Barentsz, a radiologist from Radboud University Medical Center provided a joint lecture at the ESOU 2019 annual meeting.

As has been widely discussed at this meeting, we now have three level 1a prospective clinical trials assessing the role of prostate mpMRI prior to prostate biopsy1-3.

  • PRECISION1 told us that in biopsy naïve men, 28% of men can avoid biopsy after negative mpMRI. For those with PI-RADS 3-5 lesions, MRI-targeted biopsies detected 12% more Gleason ≥3+4 prostate cancer than TRUS systematic biopsy, as well 13% fewer insignificant cancers. Furthermore, MRI-targeted biopsies required only 4 cores per patient.
  • MRI-FIRST2 told us that in biopsy naïve men, 18-21% of men can avoid biopsy after a negative mpMRI, missing 11% of clinically significant prostate cancer. Patients with Likert 3-5 lesions undergoing TRUS + MRI-targeted biopsies had no difference in detection of Gleason ≥3+4 prostate cancer (+2%) compared to those undergoing TRUS systematic biopsy; there were 14% fewer insignificant prostate cancers detected among patients undergoing TRUS + MRI-targeted biopsies.
  • 4M3 told to use that in biopsy naïve men, 49% can avoid biopsy after a negative mpMRI, missing 3-4% of clinically significant prostate cancer. Patients with PI-RADS 3-5 lesions undergoing TRUS + MRI-in bore targeted biopsies had more Gleason ≥3+4 prostate cancer detected (+12%) and 11% few insignificant cancers detected compared to those undergoing only TRUS systematic biopsy.
Drs. Radtke and Barentsz subsequently presented meta-analysis data assessing the relative sensitivity of MRI targeted biopsies compared to TRUS systematic biopsy for identifying Gleason ≥3+4 prostate cancer noting that in biopsy naïve patients MRI targeted biopsies outperformed TRUS biopsy (RR 1.15), as well as in prior negative biopsy men (RR 1.28). Second, assessing the relative sensitivity of MRI targeted biopsies compared to TRUS systematic biopsy for identifying Gleason 3+3 prostate cancer, they note that in biopsy naïve patients MRI targeted biopsies detected less clinically significant prostate cancer (RR 0.60), as well as in prior negative biopsy men (RR 0.54) compared to TRUS biopsy patients.

PI-RADS 3 lesions are equivocal for clinically significant prostate cancer. The prevalence of PI-RADS 3 index lesions in the diagnostic work-up is significant, varying between one in three (32%) to one in five (22%) men4. This varies depending on a patient cohort of first biopsies, previously negative biopsies, and active surveillance biopsies. Interestingly, the PI-RADS 3 detection rate has decreased over time from 40-50% in the early years of reading mpMRI to ~15-25% in recent years. But, as Drs. Radtke and Barentsz note, not all radiologists can read mpMRIs well. In a study published by Greer et al.5, specialists (>2000 MRIs read) had less PI-RADS 3 diagnoses than non-specialists (300-500 MRIs read). Further analysis of the PRECISION data1 notes that the PI-RADS 3 rate was 5% among central reads (experts) and 21% among total reads (non-experts). This correlates with an increased rate of PI-RADS 1-2 among experts (52%) compared to non-experts (28%). In summary, experts are more willing (and likely more confident) to categorize possible PI-RADS 3 lesions as PI-RADS 1-2 lesions than non-experts. One way to increase the appropriate categorization of PI-RADS 3 lesions is to add clinical parameters such as PSA density, which changes the positive predictive value by ~22%6. As Dr. Barentsz notes “an indicator of an expert radiologist reading mpMRIs is a ~5% PI-RADS 3 rate.”

Drs. Radtke and Barentsz summarize their counseling of patients with PI-RADS 3 lesions as follows:
  • PI-RADS 3 in screening and low-risk patients à PSA and MRI surveillance
  • PI-RADS 3 in screening and high-risk patients à Targeted + systematic biopsy
  • PI-RADS 3 and indication for biopsy à Targeted + systematic biopsy
  • PI-RADS 3 in the index lesions, forego targeting and do systematic biopsy à old fashioned, but possible
Drs. Radtke and Barentsz provided several conclusions and take-home messages to this overview of the management of PI-RADS 3 lesions:
  • The prevalence of PI-RADS 3 index lesions varies between one in three (32%) to one in five (22%) men, depending on the patient cohort of first biopsies or previously negative biopsies
  • The prevalence of clinically significant prostate cancer in PI-RADS 3 lesions varies between patient groups from one in five (21%) to one in six (16%) depending on previous biopsy status
  • PI-RADS 3 indicated “uncertainty” and is an indicator of quality. The Total PI-RADS 3 rate should be <15%
  • Management strategies should be developed for these men
  • Addition to improvements in MR imaging: clinical parameters, such as PSA density

Presented by: Jan P. Radtke, Heidelberg University Hospital, Heidelberg, Germany; Jelle O. Barentsz, Radboud University Medical Center, Nijmegen, The Netherlands

Written by: Zachary Klaassen, MD, MSc – Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia, Twitter: @zklaassen_md, at the 16th Meeting of the European Section of Oncological Urology, #ESOU19, January 18-20, 2019, Prague, Czech Republic

References:
1. Kasivisvanathan V, Rannikko AS, Borghi M, et al. MRI-targeted or standard biopsy for prostate cancer diagnosis. N Engl J Med 2018;378(19):1767-1777.
2. Rouviere O, Renard-Penna R, Claudon M, et al. Use of prostate systematic and targeted biopsy on the basis of multiparametric MRI in biopsy-naïve patients (MRI-FIRST): A prospective, multicentre, paired diagnostic study. Lancet Oncol 2019 Jan;20(1):100-109.3.
3. van der Leest M, Cornel E, Israel B, et al. Head-to-head comparison of transrectal ultrasound-guided prostate versus multiparametric prostate resonance imaging with subsequent magnetic resonance-guided biopsy in biopsy-naïve men with elevated prostate-specific antigen: A Large Prospective multicenter study. Eur Urol. 2018 Nov 23 [Epub ahead of print].
4. Schoots IG. MRI in early prostate cancer detection: how to manage indeterminate or equivocal PI-RADS 3 lesions? Transl Androl Urol 2018 Feb;7(1):70-82.
5. Greer MD, Brown AM, Shih JH. Accuracy and agreement of PIRDSv2 for prostate cancer mpMRI: A multireader study. J Magn Reson Imaging. 2017 Feb;45(2):579-585.
6. Hansen NL, Kesch C, Barrett T, et al. Multicentre evaluation of targeted and systematic biopsies using magnetic resonance and ultrasound image-fusion guided transperineal prostate biopsy in patients with a previous negative biopsy. BJU Int 2017 Nov;120(5):631-638.