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Industry Updates

New Blood Test for Prostate Cancer

An experimental blood test for prostate cancer seems to work better than the current PSA test -- and can tell whether the cancer is
spreading.The new test looks for a protein called EPCA-2 -- or early prostate cancer antigen 2. Unlike the PSA (prostate-specific antigen) protein on which the current PSA test is based, this protein isn't found in normal prostate cells.Instead, EPCA-2 occurs in relatively large amounts only in prostate cancer cells.
The test is being developed by Robert H. Getzenberg, PhD, director of urology research at Johns Hopkins University's Brady Urological Institute."We wanted to find something that really identified people with prostate cancer and not people with enlarged or infected prostates," Getzenberg
tells WebMD. "This is as close to cancer specific as we could find. We found it is very unique. It is 97% specific, meaning that if you test positive
there's only a 3% chance you don't have prostate cancer."Getzenberg has a financial interest in the test. But experts who do not stand to gain from the test agree that it has enormous potential."This not only helps tell whether you have prostate cancer, but what kind of prostate cancer you have," Getzenberg says.Getzenberg and colleagues report early studies of the EPCA-2 test in the April issue of the journal Urology.
EPCA-2 Test Beats PSA
Nobody is entirely happy with the current PSA test for prostate cancer. A man without prostate cancer can have high PSA levels. A man with advanced prostate cancer may have very low PSA levels.
Getzenberg's team tried out the EPCA-2 test on blood samples from several different groups of people. Some were known to have early prostate cancer or late prostate cancer, and some had other kinds of cancer. Some had enlarged prostates, but not cancer. Some were women, who have no prostate gland. And some were healthy men with normal PSA levels.
Both in terms of detecting cancer when it was actually there (sensitivity),and in terms of not detecting cancer when it wasn't actually there(specificity), the EPCA-2 test beat the PSA test.
More importantly, it beat the PSA test in predicting whether prostate cancer already had spread outside the prostate gland.When that has happened, standard treatments for prostate cancer -- radical prostatectomy (surgery to remove the prostate) and brachytherapy (tiny radioactive seeds implanted in the prostate)-- fail to cure.
"I predict that within the next year, this test is going to be widely used to find the guy who has prostate cancer and who, if he got radical prostatectomy, would relapse very quickly," Brawley tells WebMD. "It is going to say to this guy, 'Skip the unnecessary surgery and get pelvic
radiation and hormone treatment now.'"
Getzenberg says it will be at least two years before the test is "out on the street" with FDA approval. All of the experts who spoke to WebMD agree
that large-scale screening tests will be needed before it's known exactly how well te test works.
"What we really need to know is how this test behaves in all comers --when we don't already know whether the men being tested have prostate
cancer," Palapattu says. "It would also be important to identify men with high risk of prostate cancer vs. low risk of prostate cancer, and to test
men after prostate surgery to see whether it can predict cancer recurrence."
When -- and if -- the EPCA-2 test is approved, men will still need better prostate cancer tests.