Washington, Aug 9 (IANS): A new screening method combining a novel drug therapy and changes in prostate specific antigen (PSA) levels can detect an aggressive prostate cancer, despite negative results obtained by biopsies, according to a US study.

Produced by the prostate gland, PSA, found in blood and semen, can be detected by a blood test. Anything higher than four nanograms in a millilitre of blood can indicate prostate cancer.

The new study by NewYork-Presbyterian Hospital/Weill Cornell Medical Centre, shows that PSA can be a much more effective marker for prostate cancer when an additional drug therapy is used, than it can as a stand-alone test, which is how it is currently used by physicians, the Journal of Urology reports.

"At a time when the value of PSA is being increasingly debated, we have shown that when used in a specific way, it can be of great value in identifying men with previously undetected prostate cancer," says lead study investigator Steven A. Kaplan, professor of urology at Weill Cornell Medical College.

"We have shown that using PSA with these drugs can help us differentiate prostate cancer from benign prostate disease in patients who are difficult to diagnose. It also demonstrates a better way to use both the PSA test and these powerful drugs," says Kaplan, according to Weill Cornell statement.