New Test for Prostate Cancer May Reduce Biopsies

A new test for prostate cancer, which measures levels of the prostate cancer gene 3 (PCA3) in urine, may be useful in diagnosing prostate cancer in men who have elevated serum levels of prostate-specific antigen (PSA) but a negative biopsy and save these men from having unnecessary repeat biopsies. The conclusion comes from a study in 226 subjects reported in the March issue of Urology. This population of men with elevated serum PSA levels and a negative biopsy represent an "especially problematic group," say the researchers. An elevated serum PSA may be a sign of prostate cancer, but it may also be a false positive result due to benign prostatic hyperplasia (BPN), so these men undergo repeat biopsies. This incurs costs and carries a risk for morbidity as well as emotional turmoil, but at the moment, it is the only way to check whether there is cancer present or not. PSA is not very good at predicting whether the biopsy will find cancer — in fact, it offers "little better than a coin-toss probability," the researchers comment. This is because PSA is specific for the prostate, but it is not specific for prostate cancer.In contrast, the new PCA3 test measures levels of a gene that is overexpressed by prostate cancer cells but is not produced (or is produced only in very small amounts) by normal cells, even in BPN. The current study concludes that test was 72% specific for prostate cancer.The PCA3 urine test, known as the Progensa PCA3 Assay, was developed by Gen-Probe and was launched in Europe in November 2006. It is currently available in the United States as an analyte-specific reagent from several laboratories and is covered by several insurers. The company is planning to apply for Food and Drug Administration approval for the test.