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New way found to judge prostate cancer severity

WASHINGTON (Reuters) - A substance produced by prostate cancer cells may let doctors use a simple urine test to judge whether a man’s disease is likely to be aggressive and life-threatening, researchers said on Wednesday.

Prostate cancer is the second most common cancer in men worldwide, but doctors struggle to determine when a man is diagnosed whether the disease may kill him or not.

As a result, many men whose tumor may actually pose little threat end up getting extensive treatment, such as surgery and radiation, they may not need.

Dr. Arul Chinnaiyan of the University of Michigan and colleagues pinpointed an amino acid called sarcosine that is produced by prostate tumor cells and is present in urine that, at higher levels, indicates the cancer is more serious.

“What we see is that among men with metastatic prostate cancer, the level of this amino acid is higher in the urine compared to men with just slow-growing cancer, your run-of-the-mill, garden-variety prostate cancer,” Dr. John Wei of the University of Michigan, one of the researchers on the study in the journal Nature, said in a telephone interview.

The researchers said the idea initially would be to develop a urine test to be given to men already diagnosed with prostate cancer, and it may or may not be possible in the future to develop a new prostate cancer screening test.

Sarcosine’s role was identified using a technique called metabolomics in which scientists study the unique chemical fingerprints that cellular processes leave behind.

“One of the biggest challenges we face in prostate cancer is determining if the cancer is aggressive. We end up over-treating our patients because physicians don’t know which tumors will be slow-growing,” Chinnaiyan said.

“With this research, we have identified a potential marker for the aggressive tumors,” he said in a statement.

Sarcosine levels were elevated in about 80 percent of the metastatic prostate cancer cases studied and about 40 percent of the early-stage cases. It was absent in cancer-free men.

ROLE IN CANCER’S SPREAD

In experiments involving prostate cancer cells in lab dishes, sarcosine seemed to influence how the cancer cells grew and even their likelihood to invade into healthy tissue.

“It tells us that sarcosine may have something to do with how cancer cells manage to get out of the prostate and spread. So that’s big,” Wei said.

Cancer is much deadlier once it spreads through the body.

The researchers also said that knowing the role of sarcosine could be valuable in developing new prostate cancer drugs. Wei said it will take “several more years at least” before any sarcosine test can be used to help patients.

If a sarcosine urine test shows that a man’s cancer may be slow-growing and routine, doctors could recommend no immediate treatment and go into an “active surveillance mode,” Wei said.

But if it shows the cancer may be dangerous, doctors could recommend aggressive treatment, Wei added.

Prostate cancer kills about 254,000 a year. In the United States, 29,000 men die of it each year, making it the No. 2 cause of cancer death in men, behind lung cancer.

Editing by Michael Kahn and Eric Beech

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