Combined Imaging Approach Effectively Detects Aggressive Prostate Cancer

Christopher P. Filson, MD, MS

The combination of multiparametric MRI with a fusion-guided biopsy (MRI plus ultrasound) was more effective at detecting aggressive prostate cancer compared with either procedure alone, according to findings from a large prospective study, which also revealed potential risk factors for aggressive disease.

In the 1000-patient single-institution study, an increased risk of aggressive prostate cancer (Gleason 3+4) was directly related with age, region of interest (ROI) grade, PSA, and PSA density in men who underwent multiparametric MRI and fusion biopsy. Overall, the greatest predictor of high-risk disease was an ROI grade 5 lesion identified on MRI. These men were more than 23 times more likely to have a Gleason score ≥7 prostate cancer (n = 301; odds ratio [OR] = 23.4; 95% CI, 12.2-44.9).

Findings from the analysis shed light on the effectiveness of fusion biopsy, which is growing in popularity among community and academic practices. Data from the study were presented at the 2015 American Urological Association annual meeting by Christopher P. Filson, MD, MS.

“More and more clinicians are using multiparametric MRI in their workup of patients with prostate cancer,” Filson, from the Department of Urology at the UCLA David Geffen School of Medicine, said when he presented the findings. “We wanted to look at how well fusion biopsy performed in patients from our large cohort, and we wanted to see how accurate mapping and targeting biopsy was in detecting Gleason score 7 or greater prostate cancer.”

The large study was comprised of the 1000 men who underwent fusion biopsy between 2009 and 2014 at UCLA. The majority of men in the study were Caucasian. Patients had never had a biopsy (n = 325), had a prior negative biopsy (n = 316), or had a previous positive biopsy and were on active surveillance (n = 359).

The median age of patients was 65 years, median PSA was 5.9 ng/mL, and the median prostate volume was 44 cc. The median PSA density in patients enrolled in the trial was 0.12 ng/mL/cc. Multiparametric MRI revealed that 76% of men enrolled in the study had at least one lesion. The majority of men had a low suspicion or grade 3 lesion (39%), 29% of men were grade 4 (moderate), and 8% had grade 5 lesions (high suspicion).

In patients diagnosed with a Gleason ≥7 prostate cancer (n = 301), 46% had a PSA level ≥10 ng/mL and 48% had a PSA density of >0.15. The OR for age was 1.52 (95% CI, 1.27-1.82) and for PSA the OR was 4.36 (95% CI, 2.79-6.83; P <.05). Those with a low PSA density, a prior negative biopsy, and a PSA below 4.0 were not at an increased risk of being diagnosed with aggressive prostate cancer.

The OR for the association between PSA density and aggressive prostate cancer was 7.40 (95% CI, 4.96-11.01; P <.05). The median PSA density for men with Gleason score ≥7 prostate cancer was 0.25 ng/mL/cc compared with 0.12 ng/mL/cc for those without aggressive cancer (P <.01).

“What was most intriguing was that patients who had high PSA density tended to have 7 times the odds of having higher grade cancer compared with those with a lower PSA density,” Filson said.

A subanalysis of the study examined men who had undergone biopsy with the mapping approach alone (multiparametrics MRI), targeted alone (fusion biopsy), or a combination of mapping and targeting. With mapping biopsy alone, 181 had a Gleason score 6 prostate cancer and 181 had Gleason score 7 or greater. Among those who underwent a targeted biopsy alone, 112 were Gleason score 6 and 205 had Gleason score 7 or greater. For the combination modality, 171 men were Gleason score 6 and 265 men had Gleason score 7 or greater.

“What we found is that when we combined mapping with targeting, we identified an additional 60 cases of high risk disease compared to a targeted-only strategy,” Filson said. “But we’re not close to making this a standard of care,” he cautioned.

The limitations of the study include the multiple indications for prior biopsy, an MRI scoring system that did not use the standard Prostate Imaging Reporting and Data System (PI-RADS), and data from a single, academic tertiary center. Despite this, the study shed light on an approach that has been growing in popularity on recent years.

“The UCLA group showed that this diagnostic tool can be used to more accurately identify Gleason score 7 or higher cancer,” said panel moderator Scott Eggener, MD, associate professor of Surgery and co-director, Prostate Cancer Program at the University of Chicago.

Further studies evaluating this modality’s accuracy are ongoing. These data may be helpful for counseling men on the most appropriate biopsy procedure.

Filson C, Margolis D, Huang J, et al. MR-US Fusion Biopsy to Diagnose Prostate Cancer: First 1000 Men at UCLA. Presented at: 2015 AUA Annual Meeting; 2015 15-19; New Orleans, LA. Abstract PD30-01.

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