Experts have cast doubt on the value of a widely used test for prostate cancer.
The test can produce false positive results
US researchers found the prostate specific antigen (PSA) test did not improve survival rates.
The researchers found men screened using the PSA test died from the disease at about the same rate as those who were not checked.
The study, which looked at 1,000 men, led by Yale School of Medicine, appears in the journal Archives of Internal Medicine.
Prostate cancer is the most common form of the disease among men in the UK, with more than 27,000 new cases, and 10,000 deaths each year.
The test works by measuring levels of a protein - prostate specific antigen - in the blood.
Levels are often raised in people with prostate cancer.
However, the test is far from flawless, as PSA levels can also be raised by a benign enlargement of the prostate, or by infections of the gland.
Neither can the test tell doctors anything about the aggressiveness of a tumour.
The researchers found that combining the PSA test with a digital examination produced even worse results.
Lead researcher Dr John Concato said men should not avoid a PSA test on the basis of the findings.
He said: "The issue isn't 'black and white.'
"Rather they should recognise that substantial uncertainty exists regarding the usefulness of PSA screening among healthy men and the limitations of the test should be discussed with their doctor."
Dr Chris Hiley, of the UK Prostate Cancer Charity, said further research was needed to definitively assess the value of the PSA test.
But she said: "This research suggests that we should be looking in other directions for an effective test - one that detects the prostate cancers that might kill if left undetected.
"We are pressing the government to convene an international research conference on prostate cancer testing to assess where the most productive research is being carried out, and to focus attention on that research."