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mpmri can rule prostate biopsy in or out

Can Imaging Rule Out The Need For Biopsy?

It’s exciting to be involved in medicine at this time in history when the pace of breakthroughs has accelerated. To put it in perspective, surgery has been around since ancient times, but it took thousands of years to overcome the problems of pain, bleeding and infection. It was only in the 19th century that anesthesia, new ways to control blood loss, and antiseptics were all developed. How close are we to the day when imaging can replace needle biopsies to diagnose prostate cancer?

If you’re one of countless patients who wish the time has come, you’re not alone. We’re not quite there, but imaging can at least help indicate when a biopsy is truly necessary. I discovered an interesting study out of the Urologic Oncology Branch of the National Cancer Institute (Bethesda, MD). The article, “Low suspicion lesions on multiparametric magnetic resonance imaging predict for the absence of high-risk prostate cancer,”1 asks whether imaging can help identify the risk level of suspected prostate cancer tumors.

The background for posing this question has to do with the hit-or- miss tendency of TRUS biopsies, which are “blind” to differences in prostate tissue. The fact that one or two needles may extract a very small amount of low risk cancer gives inadequate information. Nothing else is known about the size, shape and precise location of what contained those cells. Rather than take any chances, most urologists recommend an aggressive, whole-gland treatment with its risks of impotence and incontinence. One way to look at such a decision is to think of amputating a finger because it has a sliver—in other words, overtreating the problem.

800 patients had 3T multiparametric MRI of the prostate to detect regions of interest. Two radiologists reviewed each image. Based on the multiple imaging parameters used for analysis, 125 men were identified as low risk if they had 2 or fewer parametric indications of suspicion. The men then had targeted fusion biopsies (guided by merging their MRI images with real-time ultrasound, which results in a computer-constructed image of the size, shape and location of the suspected tumor). 107 (88%) of the men turned out to no cancer or such low-risk disease that they were considered clinically insignificant, implying no need to aggressive treatment at the time of detection. The authors concluded, “The results obtained in the present study show that low suspicion lesions on mpMRI are associated with either negative biopsies or low-grade tumours suitable for active surveillance. Such patients have a low risk of harbouring high-risk prostate cancers.”

Even though we’re not at the point where imaging can provide a diagnosis with absolute confidence, 3T multiparametric MRI can help patients avoid an unnecessary biopsy that could lead to overtreatment.

1 Yerram NK, Volkin D, Turkbey B et al. Low suspicion lesions on multiparametric magnetic resonance imaging predict for the absence of high-risk prostate cancer. BJU Int. 2012 Dec;110 (11 PtB):E783-8.

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