Researchers discover a better blood test for prostate cancer

Reported by Susan Aldridge, PhD, medical journalist

A blood protein called early prostate cancer antigen-2 may provide a better basis for a prostate cancer test.
Currently, the prostate specific antigen (PSA) test is widely used for screening and testing for prostate cancer. But PSA testing sometimes gives false positives - where elevated levels do not actually indicate cancer. Researchers at Johns Hopkins University have been working on what may be a more accurate test. It's based upon a protein called early prostate cancer antigen-2 (EPCA-2).

Levels of EPCA-2 were measured in 330 patients, divided into several groups according to their PSA and prostate cancer status. Those with EPCA-2 levels of more than 30 nanograms per milliliter were considered to be at risk of prostate cancer. The test was accordingly negative in 97 per cent of those who did not have prostate cancer. Men with no evidence of disease - regardless of PSA level - and control patients with other cancers or benign conditions - all had EPCA-2 levels below 30. Around 77 per cent of those with benign prostatic hyperplasia (BPH) had EPCA-2 levels below 30, which correlates with the number that would be expected to be cancer-free (this is important because BPH is often linked with a false positive PSA result).

Ninety per cent of those with local prostate cancer had EPCA-2 levels more than 30 as did 98 per cent of those with disease outside the prostate. Finally, the new test identified 78 per cent of men with cancer whose PSA tests were normal. Clearly, a blood test based on EPCA-2 appears to have much to offer - and the researchers are now planning to move onto bigger clinical trials. If these go well, the EPCA-2 test could be available in 18 months or so.

Source
Lancet online 24th August 2006

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