Scientists have unveiled the first reliable test for diagnosing early prostate cancer.
The urine test is so accurate that it could be used to screen all older men for the disease.
Prostate cancer is the most common male cancer, killing more than 10,000 men in the UK every year.
Scientists at the University of Surrey identified a protein called EN-2, which is only produced by prostate cancer cells.
Studies show a test for the protein detects 60 to 70% of cancers.
But the false positive rate - men who are wrongly diagnosed with cancer - is just 4%.
On both counts, the new test is vastly superior to the existing PSA blood test, which detects fewer than 40% of cancers and has a false positive rate of over 50%.
Professor Hardev Pandha, who led the research, told Sky News: "I think the lack of false positives is clearly very, very encouraging.
"The technology that underlies the test is so simple that actually having a desktop apparatus in a GP's surgery would be very, very straightforward.
"It's very exciting."
Further studies are now planned.
But the results so far show the test is as accurate as NHS screening programmes for other cancers.
The scientists hope the EN-2 test could be in widespread use in 12 to 18 months' time.
Early indications also suggest high levels of EN-2 in the urine indicate aggressive tumours that need immediate surgery.
Men with lower levels could be monitored, avoiding the need for an operation which can cause impotence and incontinence.
Dr Richard Morgan, who also developed the test, said it was a significant step forward in detecting the most common male cancer.
"In conjunction with other tests and clinical signs of cancer, I think it will have a very important part to play in diagnosis and in monitoring the disease," he said.
Tim Sharp is a trustee of The Prostate Project, which largely funded the research.
As a man in his 70s, he has also had a PSA check - and longs for the certainty the new urine test would bring.
"This is brilliant. Early treatment is absolutely the key to prostate cancer. If you catch it early, you've got an 80% chance of a cure. If you catch it late, that drops down to 20%," he said.
The scientists describe their test in the journal Clinical Cancer Research.