MRI-targeted biopsy strategy increases detection of clinically significant prostate cancer compared to TRUS-guided biopsy

EBM Focus - Volume 13, Issue 13

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Reference: PRECISION trial (N Engl J Med 2018 Mar 18 early online) (level 1 [likely reliable] evidence)

  • Magnetic resonance/ultrasound (MR/US) fusion is an increasingly common strategy for selecting areas to biopsy in men with suspected prostate cancer, but large randomized trials of its usefulness are scarce.
  • The PRECISION trial randomized 500 men with clinical suspicion of prostate cancer to magnetic resonance imaging followed by an MR/US fusion-targeted biopsy, if indicated, vs. transrectal ultrasound (TRUS)-guided biopsy.
  • MR/US fusion-targeted biopsy had a higher rate of detection of clinically significant prostate cancer and a lower rate of detection of clinically insignificant cancer.

Magnetic resonance/ultrasound (MR/US) fusion uses prebiopsy magnetic resonance images superimposed on real-time ultrasound images to identify areas of the prostate likely to yield positive biopsies. Two single-center randomized trials comparing a strategy of obtaining MR/US-targeted biopsy cores alone to standard TRUS 12-core biopsy suggest that MR/US-targeted biopsy may have a similar or higher rate of detection of clinically significant cancer (Eur Urol 2016, Eur Urol 2017). In the recent PRECISION trial conducted at 25 centers, 500 men with clinical suspicion of prostate cancer and without prior prostate biopsy were randomized to MR/US fusion-targeted biopsy (software-assisted or by eye) vs. standard TRUS-guided biopsy (10-12 cores). Patients in the MR/US fusion-targeted biopsy group had multiparametric MRI followed by MR/US fusion-targeted biopsy only if multiparametric MRI was positive (region of interest with a PIRADSv2 score ≥ 3). All men had prostate specific antigen levels ≤ 20 ng/mL and results on digital rectal exam that did not indicate extracapsular disease. In the MR/US fusion-targeted biopsy group, 28% had a negative MRI result and were not biopsied. Biopsies were not performed for other reasons in 4.6% of all men. The men were followed for at least 30 days or until treatment decisions were made, and all were included in the analysis.

MR/US fusion-targeted biopsy had a higher rate of detection of clinically significant (≥ Gleason score 3 + 4) prostate cancer (38% vs. 26% with TRUS, p = 0.005, NNT 9) and a lower rate of detection of clinically insignificant prostate cancer (9% vs. 22% with TRUS, p< 0.001, NNT 8). There were differences in subsequent procedure-related adverse events and management decisions in the two groups, but statistical comparisons were not reported. MR/US fusion-targeted biopsy was associated with a lower rate of further diagnostic testing (3% vs. 16% with TRUS), less pain at site of procedure (in 13% vs. 23%), and less erectile dysfunction (in 11% vs. 16%), but a higher rate of urinary incontinence (6.1% vs. 4.9%). The two groups appeared to have similar rates of patients opting for active surveillance (11.5% vs. 11.7%) and radical treatment (27% vs. 24.2%). In patients having biopsy, the median number of cores obtained was 4 with MR/US fusion-targeted biopsy (44% positive) and 12 with TRUS-guided biopsy (18% positive).

The PRECISION trial demonstrated that a MR/US fusion-targeted biopsy strategy has a higher rate of detection of clinically significant prostate cancer and lower rate of detection of clinically insignificant prostate cancer than standard TRUS-guided biopsy. The difference in these detection rates did not appear to influence the rates of active surveillance or radical treatment, but the use of MRI to first screen for potential lesions allowed 28% of the men to avoid having biopsy. The lower frequency of biopsies, and, possibly, the lower number of cores taken from those who were biopsied may account for the numerically lower rates of most adverse events in the MR/US fusion-targeted biopsy group. The clinically significant cancer rates in men who did not have a biopsy are not known (results from another trial suggest that they may be about 4%,Eur Urol 2017). However, this does not affect the superiority of the MR/US fusion-targeted biopsy strategy as it detected higher rates of clinically significant cancer even though not all patients had biopsy. Finally, the radiologists in the PRECISION trial reported evaluating a median number of 300 prostate MRIs per year, indicating that a certain amount of expertise may be required for these findings to be transferable to other centers. Bearing in mind this caveat, a diagnostic strategy using MRI screening plus MR/US fusion-targeted biopsy may better identify men who could potentially benefit from treatment while decreasing the number of biopsies and over diagnosis of clinically insignificant prostate cancer.

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