The goals of prostate biopsy are two-fold in that it is important to detect clinically significant cancer and to ensure patient safety (do no harm). Prostate cancer detection includes screening (PSA, DRE à TRUS biopsy) and specifically selective screening based on patient age, race, family history, and shared decision making; augmented screening may include biomarkers or utilization of mpMRI. Judicious screening and detection is important given that we want to detect clinically significant prostate cancer and that prostate cancer is the second leading cause of cancer death in US men. Second, there are more than 1 million biopsies per year, and biopsy harms include overdetection, overtreatment and increasing infection rates. Specifically, there is increasing fluoroquinolone resistance (~25% of men undergoing biopsy) and infectious complications may include urinary tract infection, epididymitis, orchitis, prostatitis and sepsis. Standard TRUS biopsy is the most common modality for performing a prostate biopsy (95% of prostate biopsies). TRUS allows the urologist to visualize the contour of the prostate, however lesions are not well visualized, and biopsies via the TRUS approach are undersampled and randomly taken.
Multiparametric MRI is a useful screening tool and useful at multiple points in the evaluation of prostate cancer, providing excellent anatomic detail. Multiple sequences are obtained for a multiparametric MRI, including T1- and T2-weighted images, diffusion-weighted imagines, and dynamic contrast-enhanced images. Targeted biopsies are based on multiparametric MRI findings and are either performed in-bore, cognitively, or by MRI-US fusion biopsy:
- Cognitive fusion: includes revising the MRI and mentally noting the location of lesions to the target; this may be inaccurate especially for smaller lesions
- In-bore biopsy: performed in the MRI suite, which is resource intensive
- MRI-US fusion: this requires two visits, first for the MRI and then back for the procedure. There is a real time, 3-D map generated by the urologists and then the MRI and ultrasound are fit over one another, identifying the target
To compare MR/ultrasound fusion-guided biopsy with ultrasound-guided biopsy, Siddiqui et al.1 assessed a prospective cohort of 1,003 men with a primary objective of comparing targeted and standard biopsy approaches for the detection of high-risk prostate cancer (Gleason score >= 4+3). Targeted MR/ultrasound fusion biopsy diagnosed 461 prostate cancer cases, and standard biopsy diagnosed 469 cases. There was exact agreement between targeted and standard biopsy in 690 men (69%) undergoing biopsy. However, targeted biopsy diagnosed 30% more high-risk cancers versus standard biopsy (173 versus 122 cases, p < 0.001) and 17% fewer low-risk cancers (213 versus 258 cases, p < 0.001). The PROMIS trial included 576 men that underwent an mpMRI, TRUS-biopsy and saturation perineal biopsy.2 This approach avoided 27% of biopsies if there was a negative MRI, whereas MRI guidance identified 18% more cases of significant prostate cancer. Following PROMIS was the PRECISION trial3 which randomized 500 men to MRI directed versus standard biopsy (10-12 cores). With regards to detection of clinically significant prostate cancer (Gleason score >= 3+4), the detection rate was 38% in the MRI targeted group and 26% in the standard biopsy group. For clinically indolent prostate cancer, MRI directed biopsy detected insignificant disease in 9% of cases and 22% in the standard biopsy group. Altogether, 28% of patients in the MRI group avoided a biopsy. As follows is the percentages of men with clinically significant, clinically insignificant, and no cancer, identified according to PI-RADS v2 score:
Multiparametric MRI is also important in active surveillance, but patients should not avoid a biopsy if the MRI remains unchanged. MRI has low sensitivity for predicting progression, and there is poor association of MRI progression and pathologic progression. However, MRI with targeted biopsy prior to initiation of active surveillance decreases the chance of discontinuing active surveillance at two years, and MRI-ultrasound fusion detects significantly more grade progression compared to systematic biopsy at two years.
Transperineal biopsy has gained interest over the last several years, based on lower complication rates, local anesthesia, access to the entire gland (anterior), and no compromise in cancer detection rates. However, there is a significant learning curve, even with anesthesia patients may still be in pain, and there is significant time required to perform the procedure.
Dr. Scarpato concluded her presentation with her recommendations for prostate biopsy in 2021:
- Patient selection includes the utilization of patient factors, biomarkers, and mpMRI results
- Technique selection
- Targeted biopsies should be considered the standard of care, however we are not able to omit systematic biopsies as of yet
- If prostate biopsy is performed via the TRUS approach, consider antibiotic prophylaxis based on antibiograms
- Transperineal biopsies minimize risk of infection
- Be on the lookout for emerging data
Presented by: Kristen Scarpato MD, MPH, Assistant Professor Department of Urology, Residency Program Director Department of Urology, Division of Urologic Oncology, Vanderbilt University, Nashville, TN
Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia Twitter: @zklaassen_md during the 85th Annual Southeastern Section of the American Urological Association, April 23-24, 2021
- Siddiqui MM, Rais-Bahrami S, Turkbey B, et al. Comparison of MR/ultrasound fusion-guided biopsy with ultrasound-guided biopsy for the diagnosis of prostate cancer. JAMA. 2015 Jan 27;313(4):390-397.
- Ahmed HU, El-Shater Bosaily A, Brown LC, et al. Diagnostic accuracy of multi-parametric MRI and TRUS biopsy in prostate cancer (PROMIS): A paired validating confirmatory study. Lancet2017;389(10071):815-822.
- Kasivisvanathan V, Rannikko AS, Borghi M, et al. MRI-targeted or standard biopsy for prostate cancer diagnosis. N Engl J Med2018;378(19):1767-1777.