The PSA test has a high rate of false-positive results that suggest cancer when the disease isn't present. (CBC)

A urine test could someday help distinguish between aggressive forms of prostate cancer that need to be treated quickly and benign types, say researchers .

In Thursday's issue of the journal Nature, scientists in the U.S. say a chemical called sarcosine becomes more abundant in prostate tumours. It also seems to assist prostate cancer cells to invade surrounding tissue.

Sarcosine was also found in higher levels in the urine of patients with aggressive prostate cancer, Arul Chinnaiyan of the University of Michigan Medical School in Ann Arbor and his colleagues found.

"This is proof-of-principle that we can identify metabolites, or panels of metabolites, that might be correlated with aggressive prostate cancer versus slower-growing prostate cancer," Chinnaiyan said.

When the researchers examined 1,126 molecules produced by the body in a total of 262 samples of tissue, blood or urine, they found 10 molecules or metabolites that were present more often in advanced cancer.

Could supplant PSA test

Sarcosine seemed to be a better indicator of advanced cancer than the traditional marker, prostate specific antigen or PSA.

The researchers also looked at how sarcosine affected the behaviour of cancer cells grown in the laboratory.

After scientists added sarcosine to cultures of benign prostate cells or manipulated the biochemical pathways of the cells so they produced more sarcosine, the cells became invasive.

On the other hand, shutting down production of the metabolite in cancer cells blocked invasion.

"Thus, components of the sarcosine pathway may have potential as biomarkers of prostate cancer progression and serve as new avenues for therapeutic intervention," the study's authors concluded.

The findings, which need to be confirmed in animal models, suggest the metabolite plays an important role in the disease.

An important next step in the research is to do similar experiments on the other nine potential biomarkers identified in the study.

For reliable diagnosis of aggressive disease, "we need to have panels, not just rely on a single metabolite," Chinnaiyan said.