Prostate cancer can be hard to detect. Deciding what to do about it if we find or suspect it can be even tougher, for patients and their doctors.
Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy
Of course we want to treat aggressive, potentially lethal prostate tumors. But we don’t want patients to endure needless worry and undergo unwarranted medical procedures if their cancer is slow-growing and not life-threatening.
Fortunately, a new technology is available that should help us with both of those challenges – prostate cancer detection and differentiation. It’s called fusion guided biopsy, and Cleveland Clinic is the first medical center in Northeast Ohio to use the UroNav Fusion Biopsy System to examine patients in the biopsy procedure room.
Fusion guided biopsy, which most health insurance plans cover, is a welcome addition to our arsenal of cancer-fighting tools. Let me explain why it’s needed and how it works.
Improvements in diagnostic tools needed
The existing methods we’ve used to look for prostate cancer haven’t improved much in the last three decades. The traditional digital rectal exam isn’t a very effective screening tool; probing with a finger can only access part of the gland, so we may miss some cancers. And by the time tumors grow large enough to be felt with the finger exam, they may be at an advanced stage.
The prostate specific antigen (PSA) blood test, since 1994 a companion to the digital rectal exam for screening older men, measures levels of a protein that often go up when prostate cancer is present.
But other conditions besides cancer can elevate PSA levels. And there’s no clear-cut “normal” PSA level. Many men with a high PSA result don’t actually have prostate cancer, while some with low levels do.
If repeatedly worrisome PSA results point to the possibility of prostate cancer, we turn to a prostate biopsy to confirm the diagnosis. But like the digital rectal exam and the PSA test, this tool has limitations.
Drawbacks of random biopsy
To obtain prostate tissue for cancer testing, we poke a series of needles (between 12 and 24) into different areas of the gland, guided by ultrasound. We’ve used this method since the 1980s. The ultrasound images help us place the needles properly, but the pictures aren’t distinct enough for us to be able to tell cancerous from normal prostate tissue, so we can’t target and home in on suspicious areas for biopsy. In truth, we’re using a scattershot “blind” approach, hoping that, if a tumor is present, one of the needles will encounter it. These random biopsies can miss some harmful tumors, while turning up others that are inconsequential and may end up being treated unnecessarily.
An MRI scan is better than ultrasound at revealing details in soft tissue, such as the prostate gland. We can’t diagnose prostate cancer from an MRI image, but we can certainly use it to identify suspicious areas that warrant closer examination with a needle biopsy.
The problem, though, is that the cramped confines of an MRI chamber aren’t the ideal place to do the biopsy procedure. That’s where the new fusion guided biopsy method comes in.
A fusion of MRI and ultrasound
Recently, researchers have developed software that “fuses” those detailed MRI scans with live, real-time ultrasound images of the prostate. A patient first undergoes the MRI scan. A radiologist reviews it and marks suspicious areas.
Later, in an outpatient setting, we insert an ultrasound probe into the patient’s rectum. As we move the probe around the prostate, the fusion software shifts the overlaid MRI image accordingly, giving us a detailed 3-D ultrasound/MRI view. We can use the fused image to guide the biopsy needles precisely to the lesion we want to sample rather than poking around and hoping we find something. It’s like using a GPS to reach your destination rather than driving without directions.
As you can see in these images, an MRI scan (right) provides much more detail of the prostate than an ultrasound scan (left) does, showing a dark area (arrow) that suggests a tumor.
When the MRI and ultrasound images are fused, we get an even clearer target to biopsy. Below is the fusion guided image we see during the biopsy procedure, with the prostate outlined in red, the suspected tumor in green and the biopsy needle in yellow.
Fewer repeat prostate biopsies?
The fusion guided biopsy approach isn’t perfect. A recent study found that the fusion method missed almost as many prostate tumors as did standard biopsy. But as my Cleveland Clinic colleague, urologist J. Stephen Jones, MD, noted, the cancers that the fusion method missed were far more likely to be clinically insignificant ones.
Put another way, fusion guided biopsy is better than the existing approach at finding prostate tumors we need to treat, while overlooking those we don’t need to worry about.
Each year in the United States, about 700,000 men with worrisome PSA levels undergo repeat prostate biopsies. The fusion guided biopsy approach should help us reduce that number, by giving us better information the first time around.
This tool should also be a boon to men who’ve been diagnosed with small, slow-growing prostate tumors and who are on active surveillance – also called watchful waiting – by possibly reducing the number of biopsies they must undergo.
Prostate cancer treatment guide