New Screening Test Shows Promise for Diagnosis

"This has the potential to be a major advance in the development of more accurate tests for prostate cancer diagnosis," says Mark Stovsky urologist at UH Case Medical Center. "Prostate cancer is the most common cancer in men but traditional screening is not very accurate. This test provides a new way to look at prostate cancer diagnosis utilizing a novel biological assay which differentiates PSA molecular structures arising from cancer versus non-cancerous glands."

The accuracy of traditional prostate cancer screening (serum prostate-specific antigen or 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 55-75 percent. This finding can therefore lead to unneeded prostate biopsies and unnecessary worry in patients. Additionally, the serum PSA test carries, in some studies, false negative rates of up to 15 percent, meaning that some men with 'normal' PSA values actually have cancer. What is needed is a test that can more accurately predict the presence of prostate cancer on biopsy.

Researchers studied a urine-based test that works differently than most prostate screening methods by using a novel assay to separate PSA protein structures as being linked to either a 'cancer' or 'non-cancer' pathologic diagnosis based on ultrasound guided biopsy. Instead of attempting to find a single genetic biomarker which predicts the presence of cancer, the PSA/SIA assay is based on the assumption that there may be myriad different ultra-structural changes in the PSA protein which define the cancer phenotype. The authors theorize that the extremely high sensitivity of the test is the result of the ability of the PSA/SIA biological filter to categorize the myriad ultra-structural changes in the PSA protein as being made by either cancer versus non-cancer glands. The PSA/SIA assay was also found to have relatively high specificity (low false positive) results compared to the traditional serum PSA test.

The initial study, which followed 222 men, found that the new screening method had 100% sensitivity (no false negative results) and 80.3% specificity (low false positive results).

The technology will be tested in further clinical research studies to determine its accuracy in serum as well as its ability to predict cancer grade/aggressiveness and the response to curative intent therapies.; Source: University Hospitals Case Medical Center