Missing the Mark: Prostate Cancer Upgrading By Systematic Biopsy over MRI/TRUS Fusion Biopsy

Multiparametric MRI (mpMRI) and fusion biopsy (FBx) detect more high-risk prostate cancer (PCa) and less low-risk PCa than systematic biopsy (SBx). However, there remains a small subset of patients where SBx captures higher grade disease than FBx.

We aim to identify potential mechanisms for failure of FBx biopsy in detection of clinically significant (CS) PCa.

We reviewed a prospectively maintained database of patients undergoing mpMRI followed by FBx and SBx from 2007-2014. In patients disease upgraded to CS disease (Gleason ≥ 7) by SBx over FBx, independent re-review of MR imaging, archived biopsy imaging, and whole mount pathology, as well as needle coordinate mapping were conducted. Multivariate logistic regression analysis was performed to determine predictors for upgrading by SBx.

Disease upgrading based on SBx over FBx occurred in 135/1003 (13.5%) patients, of which only 62 (6.2%) were to intermediate (Gleason=7) [N=51, 5.1%] or high risk PCa (Gleason≥8) [N=11, 1.1%]. On multivariate analysis, lower PSA (p <0.001), higher MRI prostate volume (p <0.001), and lower number of target cores (p=0.001) were predictors of upgrading by SBx. Main mechanisms for under-grading by FBx included mpMRI reader oversight, presence of MR invisible cancer, FBx technique error, and intra-lesion Gleason heterogeneity.

MRI and FBx rarely misses CS PCa, as only 62/1003 (6.2%) cases were upgraded to CS disease by SBx. Imaging and biopsy techniques are continually refined and further studies will help to clarify mechanisms of FBx failure and patient populations which benefit from SBx in addition to FBx.

The Journal of urology. 2016 Aug 28 [Epub ahead of print]

Akhil Muthigi, Arvin K George, Abhinav Sidana, Michael Kongnyuy, Richard Simon, Vanessa Moreno, Maria J Merino, Peter L Choyke, Baris Turkbey, Bradford J Wood, Peter A Pinto

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Urologic Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland. Electronic address: ., Department of Urology, University of Michigan, Ann Arbor, Michigan., Urologic Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland., Biometric Research Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD., Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland., Molecular Imaging Program, National Cancer Institute, National Institutes of Health, Bethesda, Maryland., Center for Interventional Oncology, National Cancer Institute & Clinical Center, National Institutes of Health, Bethesda, Maryland.