Men who drink a lot of coffee appear to have a lower risk of developing a deadly type of prostate cancer -- and the more they drink, the lower the risk, researchers reported on Wednesday.
Men who consumed the most coffee -- six or more cups a day -- had nearly a 20 percent lower risk of developing any form of prostate cancer, the team at the Harvard School of Public Health found. And those men had a 60 percent lower risk of getting the most deadly form of prostate cancer, the researchers reported in the Journal of the National Cancer Institute.
The findings held for both decaffeinated and regular coffee, so caffeine is not likely the factor, the researchers said.
"Few studies have specifically studied the association of coffee intake and the risk of lethal prostate cancer, the form of the disease that is the most critical to prevent. Our study is the largest to date to examine whether coffee could lower the risk of lethal prostate cancer," said Lorelei Mucci, an associate professor of epidemiology who oversaw the study.
“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," said Kathryn Wilson, a research fellow in epidemiology who headed up the work.
One weakness in the study is that it was observational, meaning the researchers just watched to see what happened in a large group of people. Stronger results come from what are called controlled studies, when subjects are assigned a drug or behavior. This is because an action like drinking coffee could be associated with some other factor that is in fact lowering the risk of cancer.
The team looked at 47,911 U.S. men taking part in an ongoing, separate Harvard project called the Health Professionals Follow-Up Study. One of the many things the men reported on was how much coffee they drank every four years from 1986 to 2008. During that time, 5,035 of the men were diagnosed with prostate cancer and 642 either had cancer that spread or died from it.
Prostate cancer is the second most common cancer killer among U.S. men, affecting one in six men during their lifetimes. It kills about 29,000 U.S. men a year.
"At present we lack an understanding of risk factors that can be changed or controlled to lower the risk of lethal prostate cancer,” Wilson said.
Coffee is full of beneficial chemicals called antioxidants, which can stop damage to cells. People who drink more coffee have also been shown to have lower risks for Parkinson's disease, type-2 diabetes, gallstone disease, and liver cancer or cirrhosis.
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