Improved Test for Prostate Cancer on the Way

Researchers have shown that a newly developed diagnostic test for prostate cancer identifies individuals with the disease with a high degree of accuracy and have proposed that the test be considered for early screening for this very common form of cancer.

Investigators at Johns Hopkins University (Baltimore, MD, USA) developed an ELISA (enzyme-linked immunosorbent assay) test for detection of early prostate cancer antigen (EPCA) in serum samples. They used the assay to evaluate samples from 46 individuals. The test group included prostate cancer patients, healthy individuals, other cancer patients, spinal cord injury victims, and patients with prostatitis.

With the cutoff level of the test set at 1.7 absorbance units at 450 nm, only the prostate cancer patients expressed plasma-EPCA levels above the cutoff. EPCA levels were high in 11 of 12 prostate cancer patients (92%) and low in all of the healthy individuals. Only two bladder cancer patients and none of the other patients had elevated EPCA levels, so that the test was correct 94% of the time. Specificity for the healthy individuals was 100%. These findings, which were published in the May 15, 2005, issue of Cancer Research, demonstrate significant improvement over the currently used PSA (prostate specific antigen) assay. That test produces as many as 25% false-positive and 15% false- negative results.

"This new blood test, when coupled with PSA screening, may help reduce the number of both unnecessary biopsies and undetected prostate tumors,” said senior author Dr. Robert H. Getzenberg, professor of urology at Johns Hopkins University. "Once this test is refined and approved for general use, it will have an impact on the detection and treatment of prostate cancer.”




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