US researchers have come up with a way to detect the cancer earlier using gene technology.

This is the first time that somebody has demonstrated that molecular detection of prostate cancer in urine is possible

Dr Paul Cairns, Fox Chase Cancer Centre, Philadelphia

Dr Paul Cairns, of Philadelphia's Fox Chase Cancer Centre, said: "This is the first time that somebody has demonstrated that molecular detection of prostate cancer in urine is possible."

Current testing for prostate cancer relies on detecting a compound in the blood called prostate-specific antigen (PSA).

The technique has been credited with saving many lives, but misses some cases of cancer, and also turns up a large number of "false positives".

Urine tests are already used to detect bladder cancers and some kidney cancers, but had not been tried for cancer of the prostate.

Dr Cairns and his team tested tumours and urine samples from 28 men known to have surgically curable cases of prostate cancer.

Sensitive technique

They tried a sensitive new testing technique to scan for a common early genetic change which is found in 90% of prostate cancers, but not in normal tissue.

Twenty-two of the tumours showed the genetic change.

For six of these 22 tumours, the corresponding urine samples also tested positive for the same genetic change.

This indicated that, in effect, some of the cancer had spilled over into the urine.

Dr Cairns said that more research was needed to improve the technique, but that it could soon become a reliable and inexpensive way to detect prostate cancer.

Dr Cairns said: "If we can detect prostate cancer in a third of patients with a preliminary study, we are optimistic that future research and continuing improvements in molecular technology will increase the detection rate."

Prostate cancer is so common that it would be really useful to have a good screening test

Dr Lesley Walker, Cancer Research Campaign

Dr Lesley Walker, head of scientific information at the Cancer Research Campaign, said a more accurate test for prostate cancer was "desperately needed".

She said the PSA test could be influenced by factors such as whether the patient smoked, or had recently had sex.

She said: "Prostate cancer is so common that it would be really useful to have a good screening test, and this sounds promising."

However, she warned that the much work was still needed before a test could be introduced.

Other scientists are attempting to improve the accuracy of the current PSA test.

Dr Peter Gann, of Chicago's North-western University, said: "We've heard stories of men undergoing up to 14 blind biopsies of the prostate just because they have elevated PSA."