18-Gene Urine Test for Prostate Cancer to Help Avoid Unnecessary Biopsies

By LabMedica International staff writers
Posted on 19 Apr 2024

Image: The new urine-based test detects high-grade prostate cancer (Photo courtesy of U-M Rogel Cancer Center)

One of the major challenges in prostate cancer management is distinguishing between slow-growing tumors, which are less likely to cause harm, and aggressive cancers that require immediate treatment. Both the Gleason score and Grade Group (GG) system are instrumental in classifying the aggressiveness of prostate cancer. Specifically, cancers rated as Gleason 3+4=7 or Grade Group 2 (GG2) or higher are considered more likely to spread compared to Gleason 6 or Grade Group 1 prostate cancers, which are generally non-proliferative. Despite prostate-specific antigen (PSA) being a cornerstone of prostate cancer screening, standard tests frequently struggle to definitively identify cases requiring urgent treatment. Now, a new urine-based test looks at 18 genes to identify prostate cancer that requires immediate treatment over the slow-growing type.

The test, called MyProstateScore2.0, or MPS2, has been developed by researchers at the University of Michigan (Ann Arbor, MI, USA) and builds on their urine-based test developed almost a decade ago when the same team had discovered two genes that fuse to cause prostate cancer. While the original MPS test currently used evaluated PSA, the gene fusion TMPRSS2::ERG, and PCA3, the new MPS2 test now examines 18 genes associated with high-grade prostate cancer. The expansion came after the team conducted RNA sequencing of over 58,000 genes to select 54 candidates highly indicative of more severe cancers. They validated these markers against urine samples collected through another major U-M study from 2008 to 2020, involving around 700 patients who underwent prostate biopsies due to elevated PSA levels. This evaluation helped narrow the selection to 18 markers that consistently correlated with higher-grade cancers. The test still includes the original MPS markers, along with 16 additional biomarkers to complement them.

The team then went on to extend their analysis by collaborating with the Early Detection Research Network (EDRN), a consortium of over 30 laboratories across the U.S., which provided a broad, nationally representative sample base. The U-M team performed blind testing of over 800 urine samples, with results compared against patient records by the NCI-EDRN collaborators. The findings highlighted MPS2's superior ability to identify GG2 or higher cancers and its near-perfect accuracy in ruling out GG1 cancers. More importantly, MPS2 proved significantly more effective than PSA alone in reducing unnecessary biopsies. While PSA tests reduced unnecessary biopsies by 11%, MPS2 could prevent up to 41% of these procedures, demonstrating its value in improving prostate cancer diagnosis and management.

“There was still an unmet need with the MyProstateScore test and other commercial tests currently available. They were detecting prostate cancer, but in general they were not doing as good a job in detecting high-grade or clinically significant prostate cancer. The impetus for this new test is to address this unmet need,” said Arul M. Chinnaiyan, M.D., Ph.D., whose lab discovered the T2::ERG gene fusion and developed the initial MPS test. “If you’re negative on this test, it’s almost certain that you don’t have aggressive prostate cancer.”

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University of Michigan