We've said it before, and now we have to say it again - the prostate-specific antigen (PSA) blood test doesn't work. In fact, it works less well than even we thought.
A new study has found that it's failing to recognize eight out of every 10 cases of prostate cancer.
Researchers from Harvard Medical School analysed the test results of 6,691 men who had a PSA, and found that it failed to spot 82 per cent of cancer cases. The test also came up with just 2 per cent of 'false positives' - where the test detected a cancer that wasn't actually there - a pretty low rating compared to most other tests that throw up many more false positives.
So what can be done? The test currently assesses as healthy a PSA blood concentration of 4 ng/ml. If this was reduced to 2.6 ng/ml, researchers reckon that the test would detect around 36 per cent of cancers - but it would also dramatically increase the rate of false positives.
This is still not an acceptable detection rate. It's perhaps time to discard the PSA and search for a more reliable test.
(Source: New England Journal of Medicine, 2003; 349: 335-42).