The following article is part of conference coverage from the 2017 American Urological Association meeting in Boston. Renal and Urology News’ staff will be reporting live on medical studies conducted by urologists and other specialists who are tops in their field in kidney stones, prostate cancer, kidney cancer, bladder cancer, enlarged prostate, and more. Check back for the latest news from AUA 2017. 

BOSTON — Over the last decade, multiparametric MRI-transrectal ultrasound (mpMRI-TRUS) fusion biopsy has improved detection of clinically significant prostate cancer (PCa) of Gleason score 3+4 and higher while reducing overdetection of low-risk disease, according to researchers presenting at the American Urological Association 2017 annual meeting.

“We have demonstrated that the performance of mpMRI-TRUS fusion-guided biopsy improves over time while going through the learning curve,” co-investigator Abhinav Sidana, MD, of the National Cancer Institute (NCI) in Bethesda, Maryland, told Renal & Urology News. “It is likely that accumulating experience both on the part of the radiologist and the urologist contributes to this improvement, however, other factors such as software improvements may also improve cancer detection rates of CS cancers. One way this project can be impactful to the entire urology community is to provide evidence that continued commitment to MRI-TRUS fusion biopsy despite initial lack of results can be rewarded with highly significant results after a brief learning period.”

Since 2011, clinically significant PCa has been detected at significantly higher rates with fusion biopsy than with systematic biopsy following a period of learning, Dr Sidana and collaborators at NCI reported. Concurrently, clinically unimportant low-risk PCa has been detected at lower rates with fusion biopsy.

Using a database from their institution, the team compared cancer detection rates of Gleason score 3+4 or higher disease for 1528 patients during 3 distinct biopsy periods: cohort 1 (219 patients), July 2007 to 2010 (early learning period); cohort 2 (549 patients), 2011 to May 2013; and cohort 3 (761 patients), June 2013 to 2016 following introduction of the UroNav (Invivo) platform for fusion biopsy. The cohorts were similar with regard to average PSA, patient age, and racial distribution. During 2007 to 2016, each patient underwent mpMRI followed by targeted fusion biopsy and random systematic biopsy. Before 2012, the investigators used only National Institutes of Health (NIH) suspicion scores for identifying lesions on prostate MRI. Since 2012, they used both NIH suspicion scores and the Prostate Imaging – Reporting and Data System (PI-RADS) scoring system.

During 2007 to 2010, clinically significant PCa was detected at similar rates by fusion and systematic biopsy (24.7% vs 21.5% cohort 1). Starting in 2011, fusion biopsy significantly improved detection compared with systematic biopsy (31.5% vs 25.0% for cohort 2 and 36.4% vs 30.3% for cohort 3).

At the same time, overdetection of low-risk disease declined with fusion biopsy compared with systematic biospy (cohort 2: 14.5% vs 21.4%; cohort 3: 12.6% vs 19.7%, respectively).

The investigators determined that fusion biopsy improved with time by increasingly detecting clinically significant PCa. Gleason upgrading from biopsy to pathology occurred less with fusion compared with systematic biopsy, respectively, over time: cohort 1, 40% versus 53.3%; cohort 2, 32.3% versus 49.5%; and cohort  3, 29.5% versus 39.5%. Likewise, a PCa risk category upgrade after pathology occurred less with fusion biopsy (cohort 1, 40.0% vs 53.3%; cohort 2, 26.9% vs 46.2%; and cohort 3, 22.5% vs 31.0%). Detection rates of clinically significant cancer, adjusted for age and PSA, improved by 5.2% between cohort 1 and 2 and by an additional 5.2% between cohorts 2 and 3 with fusion biopsy.

Among men with a prior negative biopsy, detection of clinically significant PCa was significantly greater after 2011 (cohorts 2 and 3).

“This study shows that accuracy of fusion biopsy is dependent on multiple factors: surgeon/radiologist experience and software improvements together produce improved accuracy,” Dr Sidana said. “Advances in software allowed for even greater detection of clinically significant disease in the last cohort. In cohort 3, we used a new commercialized software platform based on a previous research model for fusion biopsy. This newer model incorporated several changes into its design to improve its ease of use and technical performance. Specific areas of improvement in the newer model include MRI image registration, the interface between MR and real-time ultrasound, the design of the ultrasound tracker, and the image calibration process.”

This study provide evidence that continued commitment to MRI-TRUS fusion biopsy despite an initial lack of results can be rewarded with highly significant results after a brief learning period, according to Dr Sidana.

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Calio B, Sidana A, Sugano D, et al. Changes in prostate cancer detection rate of fusion vs systematic biopsy over time: a single center experience. [abstract] J Urol 2017;197(4S):e19-e20. Poster presented at the American Urological Association 2017 annual meeting in Boston on May 12, 2017. Poster MP03-03.