A team of researchers at the John Hopkins Hospital in the US say that they have come up with a better alternative to the PSA to detect prostate cancer.
The new test is called EPCA-2 (early prostate cancer antigen-2) and it works in a simple blood test.
Prostate cancer, the most common malignancy in men, is one of the more perplexing areas of medicine. Physicians are unsure how to find it and when to treat it.
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).
It is in such a backdrop the new test could prove to be a more useful option. EPCA-2 is a protein that is part of the 'nuclear matrix,' the scaffolding inside a cell's nucleus that helps it copy its genes.
A team led by Robert H. Getzenberg, professor of urology and director of research at the James Buchanan Brady Urological Institute at The Johns Hopkins University School of Medicine tried the new test on 30 men with PSA readings above 2.5 and in whom biopsies found no cancer.
All had normal EPCA-2 readings (below 30 ng per ml.). This suggested that the test may eliminate many of the 'false-positive' PSA results -- readings that are abnormal but apparently do not denote cancer.
On the other hand, the EPCA-2 test appears able to detect cancer even when the tumor is small. It identified 36 out of 40 men who had cancer confined to the prostate gland, and 39 out of 40 men in whom the tumor had spread. It also identified many men -- 14 out of 18 -- who had cancer but whose PSAs were normal.
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.
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.
In a study published in the April issue of the journal Urology, Getzenberg and his team note, '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.'
Getzenberg also points out, '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.'
'We hope this will minimize the number of unnecessary biopsies,' he adds.
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.
Larger clinical trials for EPCA-2 are planned that could make this test available to the public in approximately 18 months.
Prostate cancer is diagnosed in about 230,000 American men each year, and about 30,000 die of it. The death rate is 2.5 times higher among blacks than among whites.