- A prostate cancer biomarker test that utilizes 17 genetic markers has demonstrated a high degree of accuracy in screening for serious cancer.
- The test also significantly reduced unnecessary biopsies for individuals with indolent, low-grade prostate cancer.
- The results are exciting, but questions remain as to whether the test would perform in a more racially diverse population.
Researchers have identified 17 unique genetic markers that are overexpressed by high-grade prostate cancers, which can be screened for accurately using a urine test. Experts say the test can help doctors identify serious cancers while also reducing unnecessary biopsies.
Prostate cancers are graded according to a Gleason score. The higher the grade the more likely the cancer will spread quickly and grow.
This new test could potentially help with diagnosing and treating cancer earlier and with fewer invasive measures.
Improving PSA tests for prostate cancer
The health benefits of screening for prostate cancer with a standard prostate-specific antigen (PSA) blood test have historically come with the tradeoff: the potential for unnecessary, invasive procedures, such as prostate biopsies.
However, innovations in the realm of prostate cancer biomarker tests are helping to improve diagnostic accuracy alongside PSA testing.
The results of one such biomarker test, known as the MyProstateScore 2.0 (MPS2), which were published this month in JAMA Oncology, indicate that the test is highly accurate for detecting high-grade cancers.
Researchers found that the test had a 95% sensitivity for prostate cancer of grade group 2 or greater, and 99% for grade group 3 or greater.
“It does look impressive and exciting. I definitely think this is moving the field in the right direction, which will be helpful for patients in the long term,” Geoffrey Sonn, MD, an Associate Professor of Urology at Stanford Medicine who wasn’t affiliated with the research, told Healthline.
However, questions remain about whether the test could be accurately applied to a racially diverse population, a limitation that the authors acknowledge in the research.
Adam Murphy, MD, MBA, an Associate Professor of Urology at the Northwestern University Feinberg School of Medicine, called the research, “a good addition to the literature,” but noted that there were clear limitations regarding race. Murphy wasn’t affiliated with the research.
“It’s hard to know how it performs in other ethnic minority groups,” said Murphy.
Experimental test was between 95-99% accurate
To develop the test, researchers sequenced nearly 60,000 genes, eventually identifying 54 markers of prostate cancer. They found 17 of these markers were further stratified to indicate high-grade cancer.
Research and guidelines on prostate cancer screening have increasingly focused on identifying these high-grade cancers to help with early detection and treatment.
“Prostate cancer differs from many other cancers in that there’s a subset of low-grade prostate cancers that really do not behave like cancer. They don’t spread or metastasize, and thus they pose minimal risk of harm,”Jeffrey Tosoian, MD, MPH, an Assistant Professor of Urology and Director of Translational Cancer Research at Vanderbilt University Medical Center, and lead author of the paper, told Healthline.
“We set out to improve upon existing tests through two mechanisms. One is that we identified markers that are specific for higher-grade cancers,” Tosoian said. “The other was the breadth of markers. We were able to use newer technology that allows us to capture seventeen, plus a reference gene, so eighteen genes with a single test.”
The study included 743 men with an average age of 62, and a PSA score of 5.6. The test had a 95% sensitivity among men who had a grade group 2 or greater cancer; this sensitivity improved to 99% in men with a grade group 3 or greater cancer. In practical terms, that means the test accurately identified 95 out of 100 and 99 out of 100 incidences of cancer, depending on the grade of the cancer.
“Most cancers won’t express all of these different markers. Most will only express a subset of them. And so by having more markers in a single test, it’s likely to pick up more of the higher grade cancers that exist in the population,” said Tosoian.
Reducing false positives for prostate cancer
Another major finding of the study was the expected number of unnecessary biopsies that utilizing the test avoided.
PSA testing is known to result in false positives, which can lead to anxiety and stress, so doctors have sought out other tests, such as biomarker tests, to improve accuracy. PSA is naturally secreted in the body, whether or not cancer is present, so an elevated PSA does not indicate cancer by itself. However, due to an elevated PSA level, a doctor might be inclined to order additional testing, including a biopsy.
“For a long time, someone would get a PSA blood test and if it was abnormal, they would just go straight to having a biopsy done of their prostate, which leads to lots and lots of procedures that are uncomfortable at best,” said Sonn.
In the case of the MPS2 test, however, researchers found that utilization of the test could have reduced the rate of unnecessary biopsies by an estimated 35-42%. That is a significant improvement over other biomarker tests, which have been found to avoid between 15-30% of unnecessary biopsies.
“The aim would be that MPS2 can preserve the proven benefits of PSA screening in terms of early detection of high grade cancers that can be effectively treated, while significantly reducing the potential harms of false positive testing,” said Tosoian.
Accuracy unclear in minority racial groups
Despite the findings, a major limitation of the study is whether the test would be accurate in other ethnic groups. Only 12.8% of participants in the study self-identified as Black.
Prior research has found that different ethnic groups express variance in PSA levels; that is, depending on your ethnicity, your baseline PSA level could be higher or lower than a white individual, which can affect a doctor’s decision to pursue additional screening. A study from 2022 found that Black men have higher baseline PSA levels than White or Hispanic men, but that current PSA guidance does not account for ethnicity.
“One problem is that they tend to use a one-size-fits-all approach,” said Murphy.
Furthermore, there are also established disparities in the use of screening measures, such as MRI, among ethnic groups. A study from 2021 found that Black and Hispanic patients were significantly less likely than white patients to undergo an MRI after an elevated PSA score.
It isn’t just that Black people “are at higher risk of prostate cancer and the thresholds need to be oftentimes lowered for when you wanna do a biopsy,” said Murphy.“If you are Asian or Hispanic, the thresholds that are used for the general population are mainly derived for white men. “But because they have lower risk, the thresholds are probably higher.”
The bottom line
A prostate cancer biomarker test that utilizes genes indicating high-grade prostate cancer appears highly accurate.
Experts believe the test could improve screening for high-grade prostate cancer screening, while simultaneously reducing unnecessary biopsies.
However, questions remain as to whether the test can be accurately applied to non-White ethnic groups.
New Urine Test for Prostate Cancer May Help Reduce Unnecessary Biopsies
Source: Pinoy Lang Sakalam
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