Advances in MRI technology have resulted in a new era of cancer detection beyond transrectal ultrasound (TRUS) with the use of multiparametric MRI of the prostate. The New England Journal publication of the PRECISION trial4 randomized 500 men to MRI-targeted or systematic TRUS biopsy of the prostate. The primary outcome was the diagnosis of clinically significant prostate cancer (>=3+4 Gleason score), and the secondary outcome was the diagnosis of clinically insignificant cancer. This trial demonstrated that the use of risk assessment with pre-biopsy MRI and MRI-targeted biopsy was superior to standard TRUS–guided biopsy in men at clinical risk for PCa, who were never biopsied.
In another study, the authors aimed to characterize clinically important prostate cancers (>0.5 mm, grade group >=2), missed by MRI from 100 consecutive patients who had undergone MRI and subsequent radical prostatectomy.5 This study showed that 16% of the lesions were missed by MRI, and a total of 21% were missed or underestimated.
These results demonstrate that MRI also misses a considerable percentage of clinically significant cancer. According to Dr. Pinto, this leads to uncertainty, which can lead to overtreatment. Data show that a 30-40% rate of upgrading is seen at prostatectomy after systematic biopsy, and 60% of men receiving radical prostatectomy are with grade group 1 by biopsy. It is therefore critical to reduce this uncertainty, enabling the required confidence to enroll patients in active surveillance.
A more recently published New England Journal of Medicine paper by Dr. Pinto’s group assessed whether urologists could stop performing the systematic TRUS biopsies alltogether6 and perform only MRI-targeted biopsies. This was a trial of 2,103 men undergoing both MRI tumor-targeted and systematic 12 core TRUS biopsy during the same biopsy session. The primary endpoint was the cancer detection rate, and among those who underwent radical prostatectomy, the upgrading and downgrading of grade group. The results showed that 8.8% of Gleason grade >2 would have been missed if MRI targeted biopsy was done alone (Figure 1).
Figure 1: Cancer detection according to the biopsy method used:6
When assessing the upgrading of cancer grade group after whole-mount histopathological analysis by biopsy method, upgrading rates for Gleason grade >2 at prostatectomy drop from 18.3% to 6.7% when the patient was diagnosed by combined biopsy vs. MRI targeted biopsy alone (Figure 2).
Figure 2: Downgrading and Upgrading of Cancer Grade Group after Whole-Mount Histopathological Analysis, According to Biopsy Method:6
Concluding his talk, Dr. Pinto reiterated that when comparing MRI targeted vs. systematic biopsy, there are clear advantages to MRI-targeted biopsies. However, MRI is not without limitations and can still underestimate the histologic grade. Following radical prostatectomy, upgrades to grade group 2 or higher were substantially lower when a combined biopsy was performed. Lastly, the combined biopsy approach enables urologists to have a more accurate way to diagnose PCa and forms the confidence that they have the correct information to help patients select the best treatment for their cancer.
Presented by: Peter Pinto, MD, Investigator, Urologic Oncology Branch, Head, Prostate Cancer Section, the National Cancer Institute, National Institutes of Health in Bethesda, Maryland
Written by: Hanan Goldberg, MD, MSc, Assistant Professor, Urology Department, SUNY Upstate Medical University, Syracuse, NY, USA @GoldbergHanan at the 2020 Society of Urologic Oncology Annual Meeting – December 2-5, 2020 – Washington, DC
References:
- Salami SS, Ben-Levi E, Yaskiv O, et al. In patients with a previous negative prostate biopsy and a suspicious lesion on magnetic resonance imaging, is a 12-core biopsy still necessary in addition to a targeted biopsy? BJU International 2015; 115(4): 562-70.
- de Gorski A, Rouprêt M, Peyronnet B, et al. Accuracy of Magnetic Resonance Imaging/Ultrasound Fusion Targeted Biopsies to Diagnose Clinically Significant Prostate Cancer in Enlarged Compared to Smaller Prostates. The Journal of urology 2015; 194(3): 669-73.
- Vourganti S, Rastinehad A, Yerram N, et al. Multiparametric magnetic resonance imaging and ultrasound fusion biopsy detect prostate cancer in patients with prior negative transrectal ultrasound biopsies. The Journal of urology 2012; 188(6): 2152-7.
- Kasivisvanathan V, Rannikko AS, Borghi M, et al. MRI-Targeted or Standard Biopsy for Prostate-Cancer Diagnosis. New England Journal of Medicine 2018; 378(19): 1767-77.
- Borofsky S, George AK, Gaur S, et al. What Are We Missing? False-Negative Cancers at Multiparametric MR Imaging of the Prostate. Radiology 2018; 286(1): 186-95.
- Ahdoot M, Wilbur AR, Reese SE, et al. MRI-Targeted, Systematic, and Combined Biopsy for Prostate Cancer Diagnosis. New England Journal of Medicine 2020; 382(10): 917-28.