Image-guided biopsy for diagnosis of prostate cancer can increase detection of high-risk tumors
In the largest prospective study to date of image-guided technology for identifying suspicious regions of the prostate to biopsy, researchers compared the ability of this technology to detect high-risk prostate cancer with that of the current standard of unguided prostate biopsy. The image-guided approach, called MR/US fusion biopsy, combines targeted magnetic resonance (MR) imaging with transrectal ultrasound (US) to identify regions of suspected cancer to biopsy, whereas the current standard of detection, performed with ultrasound alone, involves biopsy of the entire prostate with twelve needles to remove core samples from separate areas of the organ. In this study, researchers at the National Cancer Institute (NCI) enrolled 1,003 men between 2007 and 2014; the men underwent both targeted and standard unguided biopsies to detect the presence of prostate cancer. To be enrolled in the study, men had to have either an elevated PSA (prostate specific antigen) level or an abnormal result via a digital rectal exam, often with a history of a negative finding on a previous standard biopsy. This study appeared January 28, 2015, in JAMA. The researchers also compared the ability of the image-guided and standard approach to predict the presence of cancer in surgically-removed prostate glands.
The results of the study showed that targeted MR/US fusion biopsy diagnosed 30 percent more high-risk cancers than standard biopsy and 17 percent fewer low-risk cancers. In addition, targeted biopsy was more accurate than standard biopsy or both biopsy methods together at identifying intermediate to high-risk disease within the entire prostate after prostatectomy. When compared to standard biopsy, targeted biopsy was able to best guide the decision in whom to recommend for surgery. Ultimately, this study showed that targeted biopsy could identify more men with high-risk disease that were missed by the standard biopsy while reducing the detection of low risk disease. These improvements in risk stratification could translate into clinical benefits for men. According to the investigators, headed by Peter A. Pinto, M.D., NCI, the findings provide a strong rationale for conducting future clinical trials to determine if targeted biopsy reduces disease recurrence and death from prostate cancer. Cost will also be a consideration for future analyses since the greatest increase in cost was due to the MRI performed on each patient; other studies have shown that when the benefits of improved risk stratification are considered, the expected costs per patient are equal to that of standard biopsy procedures. Future studies will be needed to assess the ultimate clinical implications of targeted biopsy.