New studies of a blood protein recently identified at Johns Hopkins, early prostate cancer antigen-2 (EPCA-2), may change the way men are screened for prostate cancer – a disease that kills tens of thousands of men every year.
Current standards of screening and testing for prostate cancer focus on the blood protein prostate-specific antigen (PSA) along with a digital rectal examination.
Men who have more than 2.5 nanograms per milliliter of PSA are considered at risk for prostate cancer. However, PSA testing often erroneously highlights noncancerous conditions (false positives) and can miss some cases of cancer (false negatives), according to Robert H. Getzenberg, Ph.D., professor of urology and director of research at the James Buchanan Brady Urological Institute at The Johns Hopkins University School of Medicine.
Due to elevated PSA levels, approximately 1.6 million men undergo prostatic biopsies in the United States annually, and roughly 80 percent of these men have negative results, according to Getzenberg, lead author of the study. He says that of the entire population of men in the United States who have been tested for PSA, an estimated 25 million have elevated PSA levels and a biopsy of the prostate that did not reveal any prostate cancer. Conversely, roughly 15 percent of men with prostate cancer go undetected because their PSA levels are below the cutoff level, according to Getzenberg.
In a study published in the April issue of the journal Urology, Getzenberg and a team of Hopkins researchers introduce evidence in support of EPCA-2 testing as a more accurate way to identify cancer in the prostate.
?A blood test based on EPCA-2 may greatly improve our ability to accurately detect prostate cancer early and minimize the number of false positives, therefore lowering the number of unnecessary biopsies,? says Getzenberg. ?In addition, this is the first time we have a test that effectively distinguishes between men with cancer confined to the prostate and those whose disease has spread outside of the gland.?
Results of the study also revealed that EPCA-2 levels were significantly higher in patients whose cancers had spread outside the prostate compared to those with disease confided to the gland. EPCA-2 was dramatically better at separating these groups than were PSA levels, according to Getzenberg.
?This is important, since cancer that has spread outside the prostate is more deadly, which makes it even more crucial to have a tool that detects it early,? says Getzenberg.
EPCA-2 is the second prostate-cancer marker identified by Getzenberg and his team that has outperformed PSA. Last year, they discovered an unrelated, tissue-based test, EPCA-1, that also proved effective at identifying prostate cancer. The only commonality between these markers is that they were discovered using the same approach. Getzenberg says the efficacy of EPCA-1 as a test of biopsy samples is currently being evaluated.