Yearly prostate checks benefit some men aged 40 plus
Some men should have annual prostate checks once they turn 40 to spot early, treatable cancers, UK experts say.
Targeted screening would save lives, the Institute of Cancer Research team says, even though the PSA blood test it relies on is not accurate enough to offer more widely.
It was trialled in men at high genetic risk for certain cancers.
PSA is a protein made only by the prostate gland and a raised level can be a sign of cancer.
Paul Cunningham, 67 and from Plymouth, is one of those who took part in the trials.
He is glad he did because the screening picked up a cancer that he will soon have removed.
Paul's risk of getting cancer is far above the national average because of a condition he has called Lynch syndrome (LS).
He explained: "I have inherited genes that put me at higher risk."
He has already been treated for bowel cancer, and has had numerous skin cancers removed.
During the prostate screening trial, called IMPACT, his fifth annual check revealed he had an elevated PSA (prostate specific antigen) level in his blood.
Paul went for further tests and his doctors found the tumour.
He said: "Thanks to the screening, they've managed to catch my cancer early. I hope these findings will go on to help others in my position."
Why aren't all men screened?
A PSA test can give confusing results, which is why routine prostate screening is not yet offered to men.
About 75% of men who get a positive PSA test result are not found to have cancer when they go for a follow-up invasive - and sometimes painful - biopsy.
A raised PSA can be a sign of other conditions that are not cancer, such as an enlarged prostate or a urinary tract infection.
And PSA misses the tumour in about 15% of men with prostate cancer. It also cannot show whether a cancer will probably go on to cause harm.
If you're a man aged 50 or over and decide to have your PSA levels tested after talking to your GP, they can arrange for it to be carried out free on the NHS.
The IMPACT study involves 828 men at 34 centres in eight different countries.
The results so far, published in The Lancet Oncology journal, suggest targeted PSA testing is worthwhile for men with Lynch syndrome, with the benefits outweighing the risks.
Lead investigator Prof Ros Eeles said: "Our new findings show that PSA testing in men with Lynch syndrome is much more likely to pick up life-threatening prostate cancer than in the general population.
"We think that men with the gene faults causing Lynch syndrome are likely to benefit from regular PSA testing from the age of 40."
It has the potential to spot 3,000 of these cancers a year in the UK, she estimates. These tumours are more likely to be aggressive than many of the 50,000 other new cases of prostate cancer diagnosed each year.
Prof Charles Swanton, from Cancer Research UK, said: "What's needed now is research to find out how early the test can diagnose prostate cancer in this group and - like any screening programme - the potential harms and survival benefits would need to be investigated before it could be rolled out.
"We don't currently recommend the PSA test for high-risk men who are asymptomatic, but if you're concerned about your cancer risk it's important you speak to your doctor."
Hayley Luxton, Research Impact Manager at Prostate Cancer UK, said: "Research like this to identify men at higher risk is vital, but we also need to find better tests which could be used to screen everyone."
Affects 175,000 people in the UK - although only 5% of people with the condition know they have it
It is caused by an alteration in a gene called a mismatch repair gene
LS doesn't cause any symptoms
Having LS does not mean you will develop cancer, but it increases your lifetime risk
If your family has a history of developing bowel, womb or prostate cancers when they are under 50, it is possible they have the altered gene that causes LS
Knowing about the risk and having regular screening may help prevent some cancers. It may also help other cancers be found in the early stages
By Michelle Roberts, Health editor, BBC News online