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Coffee tied to lower prostate cancer risk in new study: How much did guys gulp?

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(CBS) Can sipping coffee give prostate cancer the slip?

Men who regularly drink coffee - caffeinated or decaf - are significantly less likely to develop a deadly form of the disease, according to a study published online in the May 17 issue of the "Journal of the National Cancer Institute."

Harvard researchers looked at the incidence of prostate cancer in a group of almost 48,000 American men who reported their coffee consumption every four years from 1986 to 2008, according to a written statement released in conjunction with the study.

They found that men who downed the most coffee - six or more cups a day - were nearly 20 percent less likely to develop any form of prostate cancer and a whopping 60 percent less likely to develop lethal prostate cancer (that which causes death or spreads to the bones). Guys who drank one to three cups a day had a 30 percent lower risk, the study showed.

"At present we lack an understanding of risk factors that can be changed or controlled to lower the risk of lethal prostate cancer," lead author Kathryn WIlson, a research fellow in epidemiology at Harvard, said in the statement. "If our findings are validated, coffee could represent one modifiable factor that may lower the risk of developing the most harmful form of prostate cancer."

But validation is the operative word.

"I don't recommend that men change their diets based on the results of any single study," Dr. Wilson said in an email. "We need to see if this finding is confirmed in other populations."

The researchers were at a loss to explain exactly why coffee was associated with lower risk. But they noted that coffee contains antioxidants and antiinflammatory compounds, in addition to substances that help regulate insulin levels.

Coffee has already been linked to reduced risk for type 2 diabetes, gallstones, Parkinson's disease, and liver cancer. And recent studies suggest that drinking coffee doesn't increase the risk for heart disease or stroke, according to the Harvard School of Public Health website.

Prostate cancer is the second-leading cause of cancer death among American men, after lung cancer.

The American Cancer Society has more on prostate cancer.