What is the role of MRI-TRUS fusion biopsy in the workup of prostate cancer?

Updated: Jan 14, 2019
  • Author: Lanna Cheuck, DO; Chief Editor: Edward David Kim, MD, FACS  more...
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The over-detection of clinically insignificant or low-risk cancer of the prostate by systemic or standard 12-core TRUS biopsy technique has spurred the development of a more targeted approach to obtaining prostate biopsy. MRI-TRUS fusion biopsy uses software that superimposes images obtained from MRI onto real-time ultrasound for a targeted biopsy of the prostate. This approach has shown potential in improving detection of clinically significant prostate cancer when compared with systemic prostate biopsy.

In a phase III trial that included 105 patients, MRI-TRUS fusion–guided biopsy detected prostate cancer that was missed by standard 12-core biopsy in 14.3% of cases, of which 86.7% were clinically significant, and upgraded 23.5% of cancers deemed clinically insignificant on 12-core biopsy to clinically significant prostate cancer. [28]

A prospective study in 1003 patients demonstrated the superior accuracy of MRI-TRUS fusion targeted biopsy compared with standard systemic biopsy for detection of high-risk prostate disease (Gleason score ≥4+3). [29] Targeted biopsy diagnosed 30% more high-risk cancers than did standard biopsy (173 vs 122 cases, P < 0.001) and 17% fewer low-risk cancers (213 vs 258 cases, P < 0.001). [28] When standard and targeted biopsy were combined, an additional 103 cases were diagnosed, mostly of low-risk disease. [29]

In a retrospective review by Sankineni et al of 33 patients with sub-capsular lesions evaluated by standard 12-core TRUS-guided biopsy and MRI-TRUS fusion-guided biopsy, 24 patients were found to have cancerous sub-capsular lesions. [30]  Of those 24 cases, 19 were confirmed by fusion-targeted biopsy and standard TRUS-guided biopsy; however, five lesions were identified only by fusion-targeted biopsy. [30] The improved detection of sub-capsular lesions shown in this study further supports the role of fusion-targeted biopsy, as sub-capsular lesions are commonly aggressive tumors. [30]

One disadvantage of MRI-TRUS fusion-guided biopsy is the cost of software. [31] In a retrospective study, Alberts et al used the Rotterdam Prostate Cancer Risk Calculator (RPCRC) to evaluate its potential in avoiding unnecessary MRI imaging. [32] In 122 patients who underwent multiparametric MRI (mpMRI) with subsequent MRI-TRUS fusion-guided biopsy after initially having negative TRUS, RPCRC could have avoided 62 (51%) mpMRI’s after a negative TRUS-guided random biopsy performed because of prostate-specific antigen level and/or digital rectal examination findings. [32]

With the growing acceptance of active surveillance protocols for men with localized disease, more patients are undergoing active surveillance for management of their prostate cancer. MRI-TRUS fusion-guided biopsy has the potential to add diagnostic value in identifying candidates for active surveillance.

Hu et al used targeted biopsy to determine whether Epstein criteria (Gleason score 6 or less, 2 or fewer cores positive, and 50% or less of any core) were sufficient for identifying candidates for active surveillance. [33] Targeted biopsy with mpMRI-TRUS fusion was performed in 113 patients undergoing active surveillance. [33] The likelihood of reclassification in lesions with grades 4 or 5 on mpMRI based on Standards of Reporting for MRI targeted biopsy studies (START) was 45% and 100%, respectively. [33] These rates of reclassification show the potential utility of targeted fusion biopsy for identifying candidates for active surveillance protocols.

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