US: A widely used blood test designed to look for early signs of prostate cancer misses 82 per cent of tumours in men under 60, according to a study published yesterday.
The prostate-specific antigen (PSA) test missed 65 per cent of cancers in older males, the study, published in the New England Journal of Medicine, found. The test is used in Ireland but many doctors also recommend an internal examination for greater reliability.
Dr Rinaa Punglia of Harvard Medical School and her team said the accuracy of the test had been overrated because doctors did not routinely confirm what seemed to be healthy readings on the test.
A PSA level of 4 or under is considered healthy. The American Cancer Society says a level above 4 but less than 10 indicates a 25 per cent chance of having prostate cancer. If the level goes above 10, the cancer risk rises to more than 67 per cent.
Dr Punglia's team recommended lowering the "healthy" reading to 2.6 - even though many more men who do not have prostate cancer would have to undergo painful biopsies to verify they did not have cancer.
The PSA test, approved in 1986, measures levels of prostate-specific antigen, a protein produced by the prostate gland and overproduced by prostate tumours. The test has been credited with detecting prostate cancer in its early stages 80 per cent of the time.
But the Punglia team evaluated 6,691 volunteers and found that men under 60 with prostate cancer had a "healthy" PSA reading 82 per cent of the time.
For older men, the test missed 65 per cent of the tumours.
Lowering the "healthy" threshold to 2.6 would catch more tumours, researchers said.- (Reuters)