A genetic test that identifies men most at risk of prostate cancer could be available within three years, scientists said yesterday. British doctors will use the test in screening programmes to spot the disease in its earliest stages, before it has become dangerously advanced or has spread throughout the body.

Early detection could boost the survival rate of the tens of thousands of men diagnosed with the disease in Britain every year.

Scientists began work on the test following a landmark study of nearly 2,000 cancer patients, which found seven previously unknown genetic markers that are linked to the disease. Each one raises the risk of prostate cancer by around 60%.

The findings, reported in the journal Nature Genetics, pave the way for the first reliable screening test for men at high risk of the disease, but might also lead to new drug therapies for the condition. "We are entering an era of very exciting medicine. This kind of genetic medicine will definitely happen and I definitely think it will deliver," said Dr Rosalind Eeles, lead author of the study at the Institute for Cancer Research in Sutton, Surrey.

Prostate cancer is the most common form of male cancer in developed countries and cases are rising among men under 50. Every year, more than 32,000 British men are diagnosed and 10,000 die from the disease.

Screening for the disease relies on the PSA (prostate specific antigen) blood test. Men with a high reading are usually sent for further tests and may have to undergo a biopsy, a painful procedure to remove prostate tissue for testing. But because the test is unreliable, Britain has held back from offering it to all men over the age of 50, as is now routine in the US.

The latest work, funded by Cancer Research UK, identified genetic markers that may be carried by more than half of all men with prostate cancer.

The international team led by Dr Eeles discovered the markers by comparing DNA of men with prostate cancer with DNA from healthy patients. They collected DNA samples from 1,854 men who had been diagnosed with prostate cancer by the age of 60 or younger, or who had a family history of the disease. They then gathered DNA from 1,894 men with similar lifestyles, who were known to have a low risk of prostate cancer from PSA tests.

By comparing the DNA from the two groups, the scientists identified seven "spelling mistakes" in the genetic code that were strongly linked to the cancer. One gene called MSMB seems to play a role in prostate cancer returning after treatment, but could also be used to screen for the disease. A second gene, called LMTK2 is a promising target for new drugs to treat the disease, the researchers said.

The team has now set up a new study to test whether screening men for the genetic markers helps predict who will develop the disease. If it works, doctors will be able to single out men who are most at risk for closer monitoring.

Laurie Whelan, a 69-year-old father of three from London, took part in the study after doctors discovered he had advanced prostate cancer. He was persuaded to take the test by his younger brother, who already had prostate cancer. Their older brother had previously died of the disease. "It turned out that I had a locally advanced cancer which had reached the outside of the gland," he said.

His cancer was too far developed for surgery to help, but instead he received hormone treatment and radiotherapy.

Another group of scientists based in Iceland said yesterday they will be offering a genetic test for prostate cancer after finding two new markers for the disease.