Thursday, February 12, 2009

Looking for a sign of deadly prostate cancer

It may soon be possible to distinguish aggressive prostate tumors requiring immediate treatment from those that grow slowly and can be safely ignored, a problem that has vexed oncologists and patients for decades. Looking at the complete profiles of chemicals produced by prostate tumors, researchers found that levels of sarcosine -- a simple derivative of the amino acid glycine -- are substantially higher in patients with aggressive tumors, they reported Wednesday in the journal Nature.

Levels of sarcosine in the blood could be easily and cheaply identified with a simple test that could replace or complement the prostate-specific antigen, or PSA, test now widely used in prostate cancer patients. The PSA is very useful for identifying the presence of tumors, but says little about their ultimate prognosis. Perhaps equally important as the metabolic findings, tests in laboratory dishes showed that adding sarcosine to benign tumors dramatically increased their aggressiveness, while blocking sarcosine production in aggressive tumors rendered them much less potent.

The findings may eventually lead to new ways of preventing the spread of the tumors, said Dr. Arul M. Chinnaiyan, a pathologist at the University of Michigan Medical School and senior author of the Nature paper. Prostate cancer is the most common form of cancer in American men, with an estimated 186,320 cases diagnosed last year, according to the American Cancer Society. About 28,660 men died of the disease in 2008. And 80% of men over the age of 80 develop it.
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