Targeted biopsy finds more high-risk, less low-risk prostate cancer

Last Updated: 2015-01-27

By Megan Brooks

NEW YORK (Reuters Health) - Targeted prostate biopsies that fuse magnetic resonance (MR)imaging and ultrasound detect more high-grade and fewer low-grade prostate tumors compared with standard extended-sextant biopsy, a new study shows.

With MR/ultrasound fusion biopsy, multiparametric-MRI images are electronically superimposed in real time on transrectal ultrasound images, Dr. Peter Pinto, of the National Cancer Institute, and colleagues explain in their January 27 report in JAMA.

They assessed the outcomes of 1,003 men suspected of having prostate cancer who underwent targeted biopsy and concurrent standard biopsy. The men had elevated prostate-specific antigen (PSA) levels or abnormal digital rectal exams, often with prior negative biopsy results.

Targeted MR/ultrasound fusion biopsy and standard biopsy diagnosed a similar number of prostate cancers (461 and 469, respectively). There was exact diagnostic agreement between targeted and standard biopsy in 690 men (69%), but targeted biopsy diagnosed 30% more high-risk tumors than standard biopsy (173 vs 122 cases) and 17% fewer lower-grade tumors (213 vs 258 cases).

The researchers say targeted biopsy was more accurate than standard biopsy or the two combined for intermediate- to high-risk disease on prostatectomy and had higher sensitivity (77% vs 53%).

Adding standard biopsy to targeted biopsy had "limited" value. When standard biopsy cores were combined with the targeted approach, 103 (22%) additional cases of mostly low-risk prostate cancer were diagnosed.

This preliminary study suggests that targeted biopsy could "significantly change the distribution of risk in men newly diagnosed with prostate cancer toward diagnosis of more high-risk disease," they write.

In email to Reuters Health, Dr. Pinto said, "This work lays the foundation for clinicians to move away from the current standard of non-guided prostate biopsies to this office-based image-targeted biopsy of the areas on the prostate MRI that are suspicious for cancer."

"Over time, this will likely become standard of care," he added.

"As our paper demonstrated, the current standard unguided prostate biopsy misses high-grade prostate cancer in many men. But before this office-based MRI targeted biopsy can be widely adopted in the medical community, we need to train radiologists in how to perform and read prostate MRIs and educate urologists in how to perform this new biopsy technique. In addition, as with any advance in medicine, the cost effectiveness of this new biopsy technique needs to be determined," Dr. Pinto said.

The co-authors of an editorial say the ability to fuse imaging modalities such as ultrasound with MRI is "an exciting innovation with the potential to enhance the diagnostic capabilities of unguided or single-modality image-guided biopsy," as this study shows.

"Given the role of tumor grade in pretreatment risk stratification and decision making, improvement of the accuracy of high-grade tumor detection by biopsy is desirable, and the results of this study are compelling for patients and clinicians," write Dr. Lawrence Schwartz of Columbia University College of Physicians and Surgeons in New York and Dr. Ethan Basch of the Lineberger Comprehensive Cancer Center in Chapel Hill, North Carolina, and associate editor of JAMA.

"Nonetheless, it remains unknown if use of this technique and shifts in cancer grade among patients who underwent biopsy will translate into clinically meaningful outcomes such as benefits in symptoms, functional status, or survival," they add.

The investigators and editorial writers agree that a randomized clinical trial is needed to determine patient-related outcomes with fusion imaging-guided prostate biopsy versus standard biopsy.

The study was supported by the National Cancer Institute. Dr. Pinto and a co-author hold a patent related to the MR/ultrasound fusion biopsy platform.

SOURCES: http://bit.ly/1BuUd7M and http://bit.ly/1yZcmv7

JAMA 2015.