Sensitive Urine Assay Detects Prostate Cancer

The test provides an original way to look at prostate cancer diagnosis utilizing a novel biological assay, which differentiates prostate-specific antigen's (PSA) molecular structures arising from cancer versus noncancerous glands.

Scientists at Case Western Reserve University School of Medicine collaborating with other institutions, studied a urine-based test that works differently than most prostate screening methods. They used a novel assay to separate PSA protein structures as being linked to either a “cancer” or “noncancer” pathologic diagnosis based on ultrasound-guided biopsy. Instead of attempting to find a single genetic biomarker, which predicts the presence of cancer, the Prostate-specific Antigen/Solvent Interaction Analysis (PSA/SIA) assay is based on the assumption that there may be myriad different ultrastructural changes in the PSA protein, which define the cancer phenotype.

The PSA/SIA assay determined the relative partitioning of heterogeneous PSA isoform populations in urine between two aqueous phases. The initial study, collected at three clinical sites, followed 222 men, and found that the new screening method had 100% sensitivity with no false negative results and 80.3% specificity showing low false positive results. The accuracy of traditional serum PSA is limited by both relatively high false positive and false negative rates. Current diagnostic strategies that use total PSA to determine the need for biopsy demonstrate false positive rates of approximately 55% to 75%.

The PSA/SIA assay, a product of AnalizaDx (Cleveland, OH, USA) provides ratiometric information independently of PSA concentration. In the preliminary study, analysis of the overall structurally heterogeneous PSA isoform population using the SIA assay showed promising results to be further evaluated in future studies. Arnon Chait, PhD, CEO of AnalizaDx, said, "This new assay is a complete departure from how the scientific community has looked at biomarkers for cancer. Instead of just measuring levels of proteins, we are exploring changes in structure which are associated with cancer.” The study was published online on July 22, 2011, in the journal Urology.

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Case Western Reserve University School of Medicine
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