LONDON (Reuters) - Instead of using a blood test to determine whether a man has prostate cancer, doctors might one day more accurately diagnose the condition using a new technique that measures a different compound, researchers said.
A small study showed how the test within three minutes produced a fingerprint of a chemical called citrate that falls markedly in the prostate gland as cancer develops, David Parker of Durham University in Britain said in a telephone interview.
"Citrate provides a significant biomarker for disease that may provide a reliable method for screening and detecting prostate cancer, and for the monitoring of people with the disease," said Parker, who helped design the test.
"This technique could form the basis of a simple screening procedure for prostate that could be used in outpatient departments and local hospitals."
Prostate cancer is the second most common cancer in men worldwide, after lung cancer. It kills 254,000 men a year globally.
Doctors have routinely recommended a blood test called the prostate-specific antigen, or PSA test, to men over 50 in the belief that early diagnosis and aggressive treatment for any cancer is better than standing by and doing nothing.
But many prostate tumors are slow-growing and take years to cause harm. Some studies suggest many men are living with the side effects of aggressive treatment with surgery and radiation for a cancer that may never have killed them.
In their study, Parker and colleagues focused on the compound citrate -- which provides energy for cells -- in prostate fluid because levels of the chemical decrease markedly when a man has prostate cancer, the researchers said.
The amount of citrate found in the prostate varies depending on an enzyme that is very sensitive to zinc. For men with prostate cancer, zinc levels are depressed which in turn leads to a fall in citrate.
"This technique makes it possible to analyze what is happening in the early and treatable stage of prostate cancer," Leslie Costello of the University of Maryland said. "It shows much promise as a clinical tool."
The researchers, who published their findings in the journal Organic and Biomolecular Chemistry, said the new test only requires a microlitre of fluid -- a millionth of a liter -- as a sample for their test. Researchers typically extract prostate fluid using a needle.
While promising, the technique is at least a few years away from use in hospitals and clinics because the researchers still need to conduct larger trials, Parker added.
Taking the sample is also more invasive than the common PSA test, though the researchers said in the future it may be possible to address that issue.
Reporting by Michael Kahn; editing by Dominic Evans