Fusion biopsy increases detection of high-grade PCa

Christopher P. Filson, MD, MSLos Angeles-New study findings from the Ronald Reagan UCLA Medical Center, Los Angeles add evidence supporting the potential for targeted magnetic resonance-ultrasound (MR-US) fusion biopsy to improve the diagnosis of prostate cancer.   

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The study, which was presented at the AUA annual meeting in New Orleans, included data from the first 1,000 men who underwent multiparametric MR imaging (mpMRI) prior to fusion biopsy at UCLA. All men underwent 12-core systematic mapping biopsy using the fusion biopsy device, and targeted biopsy was done in 766 men who had at least one suspicious region of interest (ROI) on mpMRI.

A Gleason score (GS) ≥7 cancer was found in 301 men, and having a “highly suspicious” lesion on multiparametric MRI (grade 5 ROI on the UCLA scoring system) was the strongest predictor of that outcome. Among 77 men who had a grade 5 ROI, 81% harbored a GS ≥7 cancer.

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Compared with men who had no suspicious lesions on mpMRI, men with a grade 5 ROI were over 20 times more likely to have a GS ≥7 cancer, reported Christopher P. Filson, MD, MS, who was a urologic oncology fellow at the David Geffen School of Medicine at UCLA at the time of the study.

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Predictors include age, PSA, prostate volume

Aside from mpMRI grade 5 ROI, variables associated with harboring GS ≥7 cancer included age, PSA, previous positive biopsy, prostate volume (inverse association), and PSA density. Of those factors, PSA density >0.15 had the strongest association; men with PSA density >0.15 had a sevenfold higher likelihood of having GS ≥7 disease compared to men with a PSA density <0.05.

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“MR-US fusion biopsy has been shown to be more accurate than traditional transrectal ultrasound-guided biopsy in small studies of various patient populations, but many of those previous studies were limited in their size, scope, and uniformity. We were interested in analyzing our experience that is based on a standard protocol and encompasses a large cohort of men enrolled into a prospective, IRB-approved database,” said Dr. Filson, who is currently assistant professor of urology at Emory University School of Medicine, Atlanta.

The 1,000 men included in the study were enrolled from 2009 to 2014. They were about evenly distributed among groups of biopsy-naïve men, those in active surveillance, and men with a prior negative biopsy. A single uropathologist (Jiaoti Huang, MD) read and graded all mpMRI images, and a single urologist (Leonard Marks, MD) performed all of the biopsies.

In addition to identifying ROI grade as an important predictor of significant prostate cancer, additional analyses indicated the benefits of combining targeted biopsy of abnormal ROIs with 12-core mapping biopsies for all patients undergoing this procedure. An analysis including only the 766 patients who had at least one suspicious lesion identified on mpMRI showed that the combination of mapping and targeted biopsy was more accurate than either technique alone for identifying GS ≥7 disease, reported Dr. Filson.

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“Using the two techniques together resulted in the identification of an additional 60 cases of high-grade cancer compared with targeted biopsy alone and another 84 high-grade cancers versus mapping alone, and it did so without significantly increasing the detection of low-risk disease,” he said.

NEXT: Generalizability 'may be limited'

Generalizability ‘may be limited’

“We acknowledge the generalizability of the findings may be limited because it is from a single institution that has used this technique for nearly 6 years, and we use our own MRI scoring system. However, we feel strongly that our results highlight the importance of combining mapping biopsies with targeted biopsies for men undergoing MR-US fusion biopsy.”

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An analysis was also conducted to determine how often significant prostate cancer was present among patients who did not have any suspicious ROIs on mpMRI. Among the men who had mapping biopsy and a negative mpMRI, 15% were found to have GS ≥7 disease.

“These data suggest we cannot be completely reassured about the absence of high-grade disease in men with a negative mpMRI,” Dr. Filson said.