Targeted MR Prostate Biopsy Identifies High-Risk Disease

Magnetic resonance targeting may improve the ability to detect high-risk prostate cancer on biopsy

medwireNews: Targeted magnetic resonance (MR)/ultrasound fusion prostate biopsy is better at discriminating between high- and low-risk prostate cancer than the standard extended-sextant biopsy, research published in JAMA suggests.

In all, multiparametric imaging followed by targeted MR/ultrasound fusion biopsy identified prostate cancer in 461 of the 1003 men referred for concurrent biopsy between 2007 and 2014, while standard biopsy detected prostate cancer in 469 men.

However, the techniques were in perfect pathological agreement for just 69% of the men who were diagnosed with prostate cancer, report Peter Pinto, from the National Cancer Institute in Bethesda, Maryland, USA, and co-authors.

Targeted biopsy was a significant 30% more likely to detect high-risk prostate cancer, defined as having a Gleason score of at least 4+3, than standard biopsy (173 vs 122 cases), and a significant 17% less likely to detect low-risk prostate cancer, classified as a Gleason score of 3+3 or low volume disease with a Gleason score of 3+4 (213 vs 258 cases).

“Although these improvements in risk stratification could translate into substantial clinical benefits, it is important to recognize that this study is preliminary with regard to clinical end points such as recurrence of disease and prostate cancer-specific mortality”, the researchers caution.

“These findings provide a strong rationale for the conduct of randomized clinical trials to determine the effect of targeted biopsy on clinical outcomes.”

They add that while combining targeted and standard biopsy results identified 22% more cases of prostate cancer than targeted biopsy alone, just 5% of these diagnoses were high risk, with 12% intermediate-risk and 83% low-risk disease.

Writing in an accompanying editorial, Lawrence Schwartz, from Columbia University in New York, USA, and Ethan Basch, from the University of North Carolina in Chapel Hill, USA, agree on the importance of confirming the immediate and downstream benefits of targeted therapy.

“The promise of this technique is that improved tumor grade classification will enable more appropriate treatment recommendations — eg, higher-intensity treatment for men with higher-risk disease and active surveillance for men with low-grade tumor”, they explain.

“It is notable that the studies that determined which patients are best suited to more or less intense treatment and which men should be classified as high risk did not use MRI-guided biopsies. Presumably those results would be augmented with the use of fusion imaging-guided biopsy, but this remains unknown.”

References

Siddiqui MS, Rais-Bahrami S, Turkbey B, et al. Comparison of MR/ultrasound fusion-guided biopsy with ultrasound-guided biopsy for the diagnosis of prostate cancer. JAMA 2015; 313: 390–397. doi:10.1001/jama.2014.17942

Schwartz LH, Basch E. MR/Ultrasound Fusion–Guided Biopsy in Prostate Cancer. What Is the Evidentiary Standard? JAMA 2015; 313: 367–368. doi:10.1001/jama.2014.17943

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