Hundreds of UK men are trying out a new screening test for prostate cancer to see if it should eventually be offered routinely on the NHS.
The test is a non-invasive MRI scan that takes images of the inside of the body to check for any abnormal growths.Scientists running the trial say it will take a few years to know if MRI will be better than available blood tests and biopsies at spotting cancers.
NHS England said it would review this "potentially exciting" development.
Why don't we already screen for prostate cancer?
The UK currently doesn't offer routine screening because there is no reliable test.
A blood test, called PSA, can check for high levels of a protein that can sometimes indicate that the person might have prostate cancer, but it is not always accurate.About three in four men with a raised PSA level will not have cancer and the test can also miss more than one in 10 cancers.
Men with a raised PSA may need more checks, such as a biopsy. This involves taking small samples of tissue from the prostate gland, using a needle, so that they can be examined under the microscope.
In some cases, this can miss a cancer that is there, fail to spot whether it is aggressive, and cause side-effects, including bleeding, serious infections and erectile dysfunction.
What is the new test?
MRI is non-invasive. It might be a way to make prostate cancer testing more reliable and maybe even do away with the need for biopsies altogether, researchers hope.
A recent UK trial in men with high PSA levels showed more than a quarter could be spared invasive biopsies.
The experts from University College London who are running the screening trial hope MRI will detect serious cancers earlier while reassuring the majority of men that they don't have cancer.
Prof Mark Emberton and colleagues say MRI is a good tool because it is relatively cheap, widely available and reliable.
Men found to have possible signs of cancer on the scan would be sent for more tests.
What is prostate cancer?
Prostate cancer kills about 11,800 men each year in the UK.
It usually develops slowly so there may be no signs or symptoms for many years.
The prostate is a small gland that sits underneath the bladder and surrounds the urethra - the tube men urinate through.
The chances of developing prostate cancer increase with age. Most cases develop in men aged 50 or older.
Men whose father or brother was affected by prostate cancer are at slightly increased risk themselves.
For many men with prostate cancer, treatment is not immediately necessary - doctors may suggest watchful waiting or surveillance.
More aggressive prostate cancer will need immediate treatment, which includes surgery and radiotherapy.
What do experts think?
Co-researcher Prof Caroline Moore said: "We know that at the moment around 6,000 men a year are diagnosed with late-stage cancer, where it is not curable.
"And we know that if we could detect those men at an earlier stage, where it would be curable, we would be in a much better position.
"The finer details are why we need this first study to work things out."
An NHS England official said: "NHS England is already rolling out some of the latest developments in MRI scanning for prostate cancer diagnosis and care.
"This new test is potentially an exciting development that the NHS will look at as more evidence becomes available."
Karen Stalbow, from Prostate Cancer UK, said: "This trial could provide an exciting step towards our ambition for a national screening programme that enables men to get the early prostate cancer diagnosis that can save more lives.
"If the results are positive, then MRI scanning could offer a non-invasive first stage of prostate cancer diagnosis in the future.
"Anything that offers men an easy and more effective way to be checked for prostate cancer is a good thing and we await the results with interest."