Homing in on prostate cancer with fusion biopsy

Left Image: The target from an MRI is merged with an ultrasound image for targeting. Right Image: The biopsy locations are captured by the MRI-Ultrasound fusion technology.

Ideally, doctors would catch every case of prostate cancer early, before it has time to grow and spread. Early detection gives men more options, whether that involves treatment or active surveillance to make sure the cancer doesn’t continue to develop.

But standard approaches can’t always locate the prostate cancer. That’s an issue for many of my patients. One man had previously had five standard biopsies, all of which were negative for prostate cancer. But he still had high levels of PSA, or prostate-specific antigen, which is a potential indicator of prostate cancer. I told him, “You really should get an MRI.”

The patient’s MRI (magnetic resonance imaging) test showed there was an abnormality in an area of the prostate where we don’t usually see tumors—one that’s difficult for us to access during a standard biopsy. So we used an advanced technique called an MRI/ultrasound fusion biopsy, which uses both MRI and ultrasound, to help detect this patient’s prostate cancer.

This patient would not have been diagnosed as early as he was without having an MRI/ultrasound fusion biopsy. And this is just one of the many examples I’ve seen of this technology’s value to patients.

The benefits of MRI/ultrasound fusion biopsy

Prostate cancer is a serious problem, both nationwide and in the Washington, D.C., area. Locally, we have a prostate cancer incidence rate of 120.1 men per 100,000. That means more than 120 men out of every 100,000 in the area have prostate cancer—a rate that’s nearly 18 percent higher than the national average.

I recommend a prostate biopsy for men who repeatedly have test results that show high PSA levels. We traditionally use an ultrasound probe to first see if there are any abnormal areas in the prostate. If there are, we target the biopsy in those areas. If there aren’t, we sample 12 random areas to see if we can locate any cancerous cells. The challenge with this approach is that it’s possible to still miss cancerous cells.

As we’ve begun to use MRI scans more often, we’re able to find tumors within the prostate. MRI scans are especially helpful for detecting aggressive prostate tumors. Many times, I see patients who have high PSA scores but negative biopsies, and prostate tumors show up on an MRI scan.

MRI/ultrasound fusion biopsy combines the best parts of MRI and ultrasound for prostate biopsies. The fusion approach starts with an MRI scan of the prostate. We then use that to guide us as we perform an ultrasound and biopsy at the same time. Merging these images is almost like having a homing device in the prostate, telling us to change angles or move our probe slightly.

MRI/ultrasound fusion biopsy combines the best parts of MRI and ultrasound for prostate biopsies. via @MedStarWHC

Following the completion of the procedure, the distribution of the biopsy sites in relation to the targets can be easily visualized.

This technique increases the number of cases of prostate cancer we’re able to diagnose, especially higher-risk cases of the disease. One study found that targetedMRI/ultrasound fusion biopsy helped doctors diagnose 30 percent more high-risk cases of prostate cancer compared to standard biopsy.

During my training at Georgetown University, I had the opportunity to train at the National Institutes of Health (NIH) for four months. The NIH is where the MRI/ultrasound fusion biopsy system was developed. I use it frequently, and other centers are starting to use it more as well.

Related reading: Can an advanced MRI improve prostate cancer screening?

MRI/ultrasound fusion biopsy harnesses the strengths of both MRI and ultrasound to do more than either can do alone. The result: We can catch more cases of prostate cancer that might not otherwise be found. My hope is that MRI/ultrasound fusion biopsy becomes the standard method doctors everywhere use to detect prostate cancer.

Request an appointment with one of our urologists if you’ve had several high PSA scores but negative prostate biopsy results in the past.

What to do when prostate cancer biopsy/PSA test results conflict

Prostate cancer can be challenging to detect. Our screening and diagnostic tools—prostate-specific antigen (PSA) testing and transrectal ultrasound-guided (TRUS) prostate biopsy—aren’t perfect. And it becomes even more difficult when those tools contradict each other.

Finding high levels of PSA, a protein made in the prostate gland, in a man’s bloodstream can indicate prostate cancer. However, PSA testing has a 15 percent false-positive rate, which means the test may detect cancer that isn’t present.

And a high PSA level usually leads to a biopsy. A TRUS prostate biopsy samples less than 1 percent of the prostate, and the false-negative rate can approach 35 percent, meaning it shows no cancer even though cancer is present.

Learn more: Should men get a PSA test to screen for prostate cancer, and when?

So what are a man and his doctor to do when his PSA level indicates he has prostate cancer but his biopsy says he doesn’t?

Your doctor may suggest doing another traditional biopsy, but because it takes random samples, it can be like trying to find a needle in a haystack. Your biopsy also may find a low-grade cancer, which means the abnormal cells are unlikely to impact your life and may only need close monitoring, not treatment. Also, there are risks associated with repeat biopsies, including bleeding and infection.

When we encounter cases like these, we turn to two advanced options to guide our decision to do a repeat biopsy: MP-MRI or checking biomarkers. These options can:

  • Rule out clinically significant prostate cancer, which can reduce your anxiety and potentially avoid a repeat biopsy.
  • Indicate you may be harboring undetected cancer, which may prompt another biopsy and, potentially, treatment.

Using MP-MRI to target prostate cancer

Multi-parametric magnetic resonance imaging (MP-MRI) has emerged over the years as an imaging test that can improve the accuracy of detecting aggressive prostate cancer.

MP-MRI uses the same machine as other MRI imaging but differs in that it uses multiple, specific imaging sequences instead of just one. If a patient has an elevated PSA level but a negative biopsy, we can use MP-MRI to detect suspicious lesions. If such lesions are found, we can target them with a biopsy using a unique platform that fuses the previously obtained MRI images with real-time ultrasound in our clinic.

When an MP-MRI shows no suspicious lesions, the results are 89 percent accurate. And in men with a prior negative biopsy, up to 87 percent of tumors detected by MP-MRI are considered “clinically significant,” which means there is a tendency for these tumors to grow and potentially become metastatic.

While we regularly use MP-MRI for repeat biopsies, it’s also being studied as a first line of testing for prostate cancer. We might be able to avoid the potential negative effects of PSA testing and biopsy by screening at-risk men with MP-MRI instead. Until we have more data on that use, we’re glad to offer MP-MRI to men whose other test results are inconclusive.

Using biomarkers to guide our next step

While MP-MRI has proven to be an effective tool in diagnosing prostate cancer, not every facility has the technology needed to perform it—the MRI machine and special biopsy platform—or radiologists with the expertise to read a prostate MRI. In addition, the test can take up to an hour in an MRI machine, which can be uncomfortable for patients, particularly if he is claustrophobic.

In these cases, biomarkers can be useful to potentially avoid repeat biopsy. Biomarkers indicate whether a certain body process is normal or abnormal. These biomarkers can pinpoint men who actually need a repeat biopsy, as well as help us find more aggressive cancers.

Types of biomarkers we can use to detect prostate cancer include:

  • Urine-based: This test looks for prostate cancer gene 3, or PCA 3. These genes make prostate cells produce a particular protein, and prostate cancer cells make more of this protein than normal cells. There are two parts to this test. First, you doctor will do a rectal exam to massage the prostate gland. This helps move the PCA3 into the urine. Then, you’ll give a urine sample. The reading will give an indication of your risk of prostate cancer. A higher PCA3 score also can indicate a higher-grade cancer.
  • Blood-based: Tests, such as the Prostate Health Index (PHI) or 4K score, are based on PSA testing but are more sensitive than PSA alone. They combine multiple biomarkers, including total PSA, free PSA, proPSA and human kallikrein-2, to come up with a score that can tell what your risk of prostate cancer might be.
  • Genomic: Noncancerous prostate tissue located near a tumor will show a “cancerization” process at the DNA level. The ConfirmMDx text looks for that process in a sample from the first biopsy in which cancer was not detected. This can indicate whether that sample is near cancerous tissue. These tests have been shown in clinical practice to decrease repeat-biopsy rates from 43 percent to 4.4 percent, helping men avoid unnecessary biopsies.

If a biomarker test suggests that the initial biopsy failed to diagnose prostate cancer, a repeat biopsy is recommended. Ideally, you would get an MP-MRI, but if you don’t have access to that technology, you may get a traditional prostate biopsy. However, if a traditional biopsy still doesn’t find high-grade prostate cancer despite biomarkers indicating it, you may want to travel to the nearest facility with MP-MRI.

A high PSA level and negative biopsy can certainly cause you and your doctor to feel nervous. But MP-MRI and biomarkers can provide reassurance that our next step is the right one.

If you’re considering your next step after a high PSA result and negative biopsy, or you want to know what type of prostate cancer screening you may need, request an appointment with one of our doctors.