The World Health Organization already recommends the controversial procedure based on research showing it lowers heterosexual men's risk of contracting HIV, the virus that causes AIDS.

Last year, scientists also reported that wives and girlfriends of circumcised men had lower rates of infection with human papillomavirus or HPV, which in rare cases may lead to cervical and other cancers. And last week, researchers reported that African men who were circumcised were less likely to be infected with a particular herpes virus.

The new work jibes with those findings, but it falls short of actually proving that removing a boy's foreskin will cut his future cancer risk, said Dr. Jonathan L. Wright, who led the research.

“I would not go out and advocate for widespread circumcision to prevent prostate cancer," Wright, of the Fred Hutchinson Cancer Research Center in Seattle, told Reuters Health."We see an association, but it doesn't prove causality."

The results were published Monday in the journal Cancer and add to the longstanding debate over whether boys should keep their foreskin.

Although most Americans men are circumcised, the procedure has become less popular over the past decade, and various groups have spoken out against it.

In September, the Royal Dutch Medical Association discouraged circumcision, calling it a “painful and harmful ritual." And a few weeks later, California Governor Jerry Brown struck down an effort to ban circumcision in San Francisco arguing it would infringe on religious freedom.

CANCER-VIRUS LINK?

For their study, Wright and his colleagues compared two groups of more than 1,600 men who had answered questions about their medical history, sex life and whether or not they were circumcised.

Half of the men had prostate cancer, while the other half didn't.

In the cancer-ridden group, 69 percent of the men had been circumcised, while that was the case for 72 percent of the comparison group, suggesting a small protective effect of the practice.

Even after accounting for a host of other factors -- such as age, race and whether or not the men had been screened for prostate cancer -- those without a foreskin still had a 15 percent lower risk of the disease. Only men who'd been circumcised before they became sexually active were at lower risk.

The foreskin is prone to tiny tears during sex, which may help bacteria and viruses enter the bloodstream.

Wright said some viruses can trigger cancer when they get incorporated into human DNA. Another possibility is that sexually transmitted microorganisms could lead to cancer by causing chronic inflammation.

That might help explain the link found by several research groups between prostate cancer and various types of sexually transmitted infection.

One in six American men will get prostate cancer during his lifetime, although only a minority of them will die from the disease.

While some doctors advocate screening for the disease, the government-backed U.S. Preventive Services Task Force has released a draft proposal recommending against it.

Wright said his study -- the largest and most comprehensive of its kind so far -- was focused on shedding light on cancer development, rather than prevention.

“We need to do more work to try to understand this," he said. “Our overarching goal is to understand how cancer develops in people."

SOURCE: bit.ly/h73jcS Cancer, online March 12, 2012.

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