Scientists Explore Virus-Prostate Cancer Link

If proven, research could lead to a vaccine, experts say

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HealthDay Reporter

TUESDAY, Jan. 16, 2007 (HealthDay News) -- Scientists are unraveling the secrets of a virus found in prostate cancer patients that might spur the disease.

In a new study, a U.S. team of researchers says the virus appears to be an infectious retrovirus with the ability to hijack body cells. Retroviruses are a family of viruses that include HIV.

There's no indication yet that the virus could cause or worsen prostate cancer, but the study authors are intrigued by the prospect.

"We have a long way to prove that it's a cause-and-effect, but it's a possibility," said study co-author Robert H. Silverman, a professor and researcher at the Cleveland Clinic. "Another question is whether the virus is associated with other kinds of cancer besides prostate cancer."

It's not uncommon for contagious viruses to be connected to cancer. For example, a sexually transmitted virus known as HPV (human papilloma virus) is considered a major cause of cervical cancer.

Last year, researchers from Cleveland Clinic and the University of California at San Francisco reported the existence of the prostate cancer-linked retrovirus, known as XMRV. They found it in prostate cancer patients and suspected it may have something to do with the disease.

According to the Prostate Cancer Foundation, prostate cancer strikes one in six American men and is the most prevalent form of non-skin cancer in the United States. Risk rises with age, with more than 65 percent of all cases diagnosed in men over the age of 65.

The new study, published in this week's issue of the Proceedings of the National Academy of Sciences, found that XMRV is infectious and works by taking over the reproductive machinery of cells and making them create more virus.

The researchers also found that the medication interferon seemed to kill the virus.

The infectious nature of the virus raises the question that it could be contagious, perhaps through sex, Silverman said.

If the virus does cause prostate cancer, "that would have significant implications," he said. "There could be early screening, and maybe it could be done on men much younger than ages 40 to 50."

Discovery of a virus that causes cancer could also lead to antiviral medications -- such as those that treat HIV -- and even a vaccine, Silverman said.

However, it's also possible that the virus may not cause prostate cancer. "We should know a lot more in one to two years," Silverman said.

For now, researchers are developing ways to test for the virus and potentially explore its effects on animals.

Dr. Bruce Roth, a professor of medicine and urologic surgery at the Vanderbilt-Ingram Cancer Center, said the findings are worthy of more research, and he agrees that a cause-and-effect relationship between the virus and prostate cancer could lead to a vaccine or antiviral drugs.

Even if only a small percentage of prostate cancer cases are connected to the virus, that could mean a "a huge step forward" in treatment, he said.

More information

For more on prostate cancer, head to the Prostate Cancer Foundation.

SOURCES: Robert H. Silverman, Ph.D., professor and researcher, Cleveland Clinic; and Bruce Roth, M.D., professor, medicine and urologic surgery, Vanderbilt-Ingram Cancer Center, Nashville, Tenn.; Jan. 15-19, 2006, Proceedings of the National Academy of Sciences

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