(UroToday.com) The 2022 American Urological Association (AUA) Annual Meeting included the International Prostate Forum session and a presentation by Dr. Behfar Ehdaie discussing MRI utilization, specifically evidence review, guidelines statements, and how to use MRI. Dr. Ehdaie started by emphasizing that what we are striving to accomplish for patients with prostate cancer is early detection of clinically significant disease, in order to prevent prostate cancer mortality. Importantly, endpoints in imaging studies have relied on sensitivity and specificity in single-arm studies, or compared detection of clinically significant disease between various modalities. However, Dr. Ehdaie notes that we rarely measure benefit to the actual patient. The pitfalls of defining clinically significant disease in the absence of long-term follow-up ignores the complexities of the proportion Gleason grade patterns versus disease volume.
With regards to discussing the technical specifications of MRI, Dr. Ehdaie notes the following points:
- 3T image acquisition (1.5T for patients with a pacemaker)
- 3-4 mm slice thickness
- T1W (axial), T2W (axial, sagittal, coronal)
- Functional sequence: diffusion weighted
- DCE: may lead to nephrogenic toxicity, with a lack of evidence for detection of high-grade prostate cancer
- Report findings using PI-RADS v2
Data from the STHLM3 consortium suggests that incorporating MRI in population-based prostate cancer screening decreases biopsy procedures with no difference in detection of higher grade cancer:1
Notably, recommendations for MRI as a stand-alone test in population-based prostate cancer screening is not supported in the AUA and EAU guidelines. Dr. Ehdaie notes that this is likely secondary to several reasons, including (i) cost, (ii) heterogeneity in quality/radiologist interpretation, (iii) mpMRI missing 35% of higher grade prostate cancer foci using whole mount specimens, and (iv) alternative tools for risk stratification, such as risk calculators, free/total PSA, and digital rectal examination. However, patients enrolled in the PLCO cancer screening study with a negative systematic biopsy (pre-MRI era) are at a very low risk of prostate cancer mortality. Dr. Ehdaie notes that MRI prior to prostate needle biopsy is recommended by the AUA and EAU guidelines to increase detection of higher grade prostate cancer based on level 1 evidence from the PRECISION trial [2]. Importantly, combining MRI-targeted and systematic prostate biopsy in patients who are biopsy-naïve increases detection of higher grade cancer, as highlighted from the following table in the EAU guidelines:
In men with a prior negative biopsy, an MRI prior to biopsy is recommended by the AUA and EAU guidelines, with the AUA guidelines recommended a systematic and MRI-targeted biopsy. Based on data from a nationwide analysis of risk of prostate cancer diagnosis and mortality following an initial negative transrectal ultrasound biopsy,3 Dr. Ehdaie emphasized that patients with a prior negative systematic biopsy (in the pre-MRI era) are at a very low risk of prostate cancer mortality:
Importantly, we must be aware that MRI-targeted prostate biopsy cores are reassigning Gleason Grade with an unknown clinical significance. Based on the PRECISION data [2], despite the total number of patients with cancer detected being the same, patients undergoing MR-targeted biopsy are reclassified with higher grade cancer and treated aggressively:
Switching gears to discuss MRI in active surveillance, Dr. Ehdaie notes that MRI is recommended to select patients to select those appropriate for active surveillance by the AUA and EAU guidelines. In the ASIST trial, published in 2020, the 2-year follow-up in this cohort revealed a lower rate of upgrading and a 50% reduction in the rate of active surveillance failure in the MRI cohort [4]. Additionally, MRI targeted biopsies improves detection of disease reclassification/progression for men on active surveillance. However, replacing periodic surveillance biopsies with MRI fails to detect many higher grade prostate cancers. Based on the MSKCC active surveillance data [5], if there were 1,000 men and we only performed surveillance biopsy on those men with MRI score increases or clinical stage increases at 3 years, we would perform 313 biopsies and avoid 687 biopsies. However, we would only diagnose 149 of 304 Gleason Grade 2 or higher disease, missing 154 men (51%) with clinically significant prostate cancer.
For prostate cancer detection in Dr. Ehdaie’s practice, he does the following:
- Repeat free/total PSA
- Obtain a 4K/PHI test or use a risk calculator
- Order an mpMRI
- For PI-RADs 4-5 lesions: MR-targeted + systematic biopsy
- For PI-RADs 3 lesions: MR-targeted + systematic biopsy in patients with a >10% risk of higher grade prostate cancer (based on 4K/PHI or risk calculator)
- Incorporate disease volume and cautiously reassign disease risk based on higher grade cancer (ie. Gleason grade 2) detected only in the MRI-targeted cores
For active surveillance in Dr. Ehdaie’s practice, he does the following:
- MRI-targeted + systematic biopsy to select patients
- Surveillance mpMRI every 18 months and consider early MR-targeted prostate biopsy if there is a new PI-RADS 4-5 lesion
- MRI-targeted + systematic biopsy every 3 years
- Incorporate disease volume and cautiously reassign disease risk based on higher grade cancer (ie. Gleason grade 2) detected only in the MRI-targeted cores
Dr. Ehdaie concluded his presentation by discussing the utilization of MRI with the following take-home messages:
- All guidelines recommend incorporating mpMRI in the detection of prostate cancer and management for men enrolled in active surveillance
- The clinical significance of Gleason grade reclassification based only on MRI-targeted cores is unknown
- We should cautiously assign a higher clinical risk to patients with higher Gleason grade detected on MRI-targeted biopsy
- mpMRI should not replace periodic surveillance biopsies on active surveillance
Presented By: Behfar Ehdaie, MD, MPH, Memorial Sloan Kettering Cancer Center, New York, NY
Written By: Zachary Klaassen, MD, MSc – Urologic Oncologist, Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia, @zklaassen_md on Twitter during the 2022 American Urological Association (AUA) Annual Meeting, New Orleans, LA, Fri, May 13 – Mon, May 16, 2022.
References:
- Eklund M, Jaderling F, Discacciati, et al. MRI-targeted or standard biopsy in prostate cancer. N Engl J Med. 2021 Sep 2;385(10)908-920.
- 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.
- Kawa SM, Stroomberg HV, Larsen SB, et al. A nationwide analysis of risk of prostate cancer diagnosis and mortality following an initial negative transrectal ultrasound biopsy with long-term follow-up. J Urol. 2022 Feb 25 [Epub ahead of print].
- Klotz L, Pond G, Loblaw A, et al. Randomized Study of Systematic Biopsy Versus Magnetic Resonance Imaging and Targeted and Systematic Biopsy in Men on Active Surveillance (ASIST): 2-year Postibiopsy Follow-up. Eur Urol 2020 Mar;77(3):311-317.
- Chesnut GT, Vertosick EA, Benfante N, et al. Role of changes in magnetic resonance imaging or clinical stage evaluation of disease progression for men with prostate cancer on active surveillance. Eur Urol. 2020 Apr;77(4):501-507.