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New Potential for Predicting Aggressive Prostate Cancer

A simple urine test might someday be used to determine if men have a fast-growing, aggressive form of prostate cancer by identifying small molecules, called metabolites, which are associated with this condition, according to a report in the medical journal Nature.

Such a test could help identify those who need aggressive treatment and might one day lead to the development of new therapies.

"There are metabolites that might be useful in predicting aggressiveness of prostate cancer," says lead researcher Dr. Arul Chinnaiyan, director of the Michigan Center for Translational Pathology and a professor of pathology and urology.

"Metabolites, similar to genes and proteins, should also be measured in understanding cancer," he says. "They have been under-appreciated relative to genes being profiled in cancer. This approach could be extended to other cancers."

However, before a urine test involving metabolites could become standard medical practice, it would have to be tested in animals and then in people through clinical trials, notes Dr. Chinnaiyan.

New Marker Better than PSA Test

For the study, Dr. Chinnaiyan's group analyzed 1,126 metabolites from 262 tissue, blood, and urine samples taken from men with early, advanced, and metastatic prostate cancer.

From these samples, the researchers identified 10 metabolites that frequently appeared with prostate cancer and most notably with advanced prostate cancer.

One of the 10 metabolites, called sarcosine, was the most indicative of advanced prostate cancer, the researchers found. Sarcosine levels were elevated in 79 percent of the samples from men with metastatic cancer (cancer that has spread) and in 42 percent of the samples from men with early stage disease.

No trace of sarcosine was found in samples from men who did not have prostate cancer, the researchers note.

According to the report, sarcosine was a better indicator of advanced prostate cancer than the current marker for the disease, prostate specific antigen (PSA).

Dr. Chinnaiyan notes that because of sarcosine's relationship with invasive cancer, future drug development may include developing compounds to block sarcosine.

The findings are preliminary, though, and it may be years before a test or treatment based on the metabolite would be available.

Ideally, he says, researchers would like to find other metabolites associated with prostate cancer that would help predict the course of the disease with even more precision.

More than 186,000 men in the US will be diagnosed this year with prostate cancer, and almost 29,000 will die from the disease, according to the American Cancer Society.

Michael M. Shen, Ph.D., a professor of medicine, genetics, and development at Columbia University College of Physicians and Surgeons in New York City, and co-author of an accompanying journal article, says the report advances the use of metabolites in understanding cancer.

"The hope is that this approach will ultimately yield a clinical application," says Dr. Shen. "For example, one could screen urine from men and not only diagnose prostate cancer but have information that would be useful for cancer prognosis."

However, that goal is a long way off, he adds.

Marker May Be Target for Therapy

"The importance of the paper is that there is a new methodology that has not been pursued extensively before, which in combination with existing approaches may yield advances in cancer diagnosis and prognosis," says Dr. Shen.

Dr. Margaret K. Offermann, the deputy national vice president for research at the American Cancer Society, stresses that studies are needed to see if the approach could be used in patients.

"This is not a perfect test," says Dr. Offermann. "It is not perfectively predictive of when someone is going to have prostate cancer and when that cancer is going to misbehave, but it may help in combination with PSA," she says.

It could also be a new target for treatment. "Potentially, by blocking the formation of sarcosine or related compounds, it may actually help in the treatment," Dr. Offermann explains.

Always consult your physician for more information.