(UroToday.com) The joint session of the European Association of Urology (EAU) and the Canadian Urological Association at the 2021 EAU annual meeting included a discussion on PSA, Imaging and Beyond for assessing men for prostate biopsy and a presentation by Dr. Nicolas Mottet about keeping the process simple. Dr. Mottet notes that an indication for biopsy should be reserved for when a diagnosis is needed, in an asymptomatic man with an abnormal DRE or elevated PSA, and occasionally in symptomatic men (if the symptoms are possibly related to prostate cancer). For men with an abnormal DRE when the PSA is <2 ng/ml the positive predictive value for a positive biopsy is up to 30%. For men with an elevated PSA, it is not specific if limited to one lab value and must be rechecked (in the same lab) after several weeks to standardize conditions.
With regards to PSA, the balance is always between sensitivity and specificity, with the most common PSA threshold of 3 or 4 ng/mL. Dr. Mottet notes that there are ways to improve PSA accuracy, such as:
- PSA density: this calculation had essentially disappeared, but is currently being used more readily
- PSA velocity or PSA doubling time: has low utility given the background noise of BPH
- Free PSA
Taken together, Dr. Mottet notes that using just the PSA/DRE is not so simple, which is why the EAU guidelines has a strong recommendation stating that “in asymptomatic men with a PSA level between 2-10 ng/mL and a normal DRE, use one of the following tools for biopsy indication: risk calculator or imaging.” Risk calculators are based on large cohorts with the aim to ascertain if a biopsy is needed. As follows are the numbers for biopsy reduction and missed prostate cancers based on different risk thresholds for the ERSPC RPCRC, PCPT 2.0 + freePSA, PCPT 2.0, and Sunnybrook risk calculators:
Risk calculators can be improved when used in combination with mpMRI. Mortezavi et al.1 assessed previously published prostate cancer risk calculators incorporating MRI data, and compared their performance with traditional risk calculators (ERSPC 3/4 and PBCG). For each patient, the probabilities of detection of clinically significant prostate cancer defined as Gleason score ≥3 + 4 was calculated. Overall, the discriminative ability of MRI risk calculators 1-4 for the detection of clinically significant prostate cancer was superior (AUC 0.81-0.87) to the traditional risk calculators (AUC 0.76-0.80):
Dr. Mottet notes that there is a direct link between PI-RADS v2 lesions and ISUP grade of prostate cancer as depicted in the following table:
Dr. Mottet also emphasized the added value of targeted biopsies, highlighting the missed lesions if the targeted biopsy were omitted:
- Biopsy naïve: 6.3%-7.6% ISUP >=2; 3.2%-6% ISUP >=3
- Repeated biopsy patient: 9.6% ISUP >=2; 6.3% ISUP >=3
On the other hand, the added value of systematic biopsies is highlighting by noting the missed lesions if the systematic biopsy were omitted:
- Biopsy naïve: 4.3%-5.2% ISUP >=2; 1.2%-4.1% ISUP >=3
- Repeated biopsy: 2.3% ISUP >=2; 1.1% ISUP >=3
The major prerequisite is MRI reproducibility, given that reproducibility between readers is moderate at best, but improvement is possible, especially with the use of multidisciplinary feedback from urologists, radiologists, and pathologists. When including MRI in the risk calculator, there are several challenges that are not so simple, according to Dr. Mottet:
- Reliability is questionable: looking at six MRI-based risk calculators, 3 showed distinct benefits and 3 were harmful compared to the “biopsy all” strategy. Thus, improvement is needed to recalibrate these risk calculators based on local prevalence
- Accuracy of targeting the lesion: the optimal number of cores/target is 3-5, but the optimal approach of MR/US fusion vs cognitive is still unclear. However, operator experience is a major factor
Dr. Mottet concluded his presentation by highlighting his recommendations for ‘keeping it simple’:
- If a diagnosis will be beneficial to the patient and a DRE or PSA (<10 ng/mL on repeat testing) is abnormal, use a risk calculator to aid in the discussion with the patient. If no mpMRI is possible, then a systematic biopsy is an acceptable approach according to the EAU guidelines. If a mpMRI is available, it should be performed before the first biopsy, targeting all lesions that are PI-RADS >=3 in addition to a systematic biopsy. If the mpMRI is normal, then a shared-decision making approach should be used to decide whether a biopsy should or should not be performed
- In the setting of a repeat biopsy, perform a mpMRI and target PI-RAD >=3 lesions (safely omitting the systematic biopsy), and when the mpMRI is normal, again, use a shared-decision making approach with regards to proceeding with biopsy
Presented by: Nicolas Mottet, MD, PhD, University Jean Monnet St Etienne, Saint-Etienne, France
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 2021 European Association of Urology, EAU 2021- Virtual Meeting, July 8-12, 2021.
References:
- Mortezavi A, Palsottir T, Eklund M, et al. Head-to-head Comparison of Conventional, and Image- and Biomarker-based Prostate Cancer Risk Calculators. Eur Urol Focus. 2021 May;7(3):546-553.