Men who regularly drink coffee appear to have a lower risk of developing a lethal form of prostate cancer, according to a new study led by Harvard School of Public Health (HSPH) researchers. What's more, the lower risk was evident among men who drank either regular or decaffeinated coffee.

The study was published in an online edition of the Journal of the National Cancer Institute.

"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 senior author Lorelei Mucci, associate professor of epidemiology at HSPH. Lethal prostate cancer is cancer that causes death or spreads to the bones.

Prostate cancer is the most frequently diagnosed form of cancer and the second leading cause of cancer death among U.S. men, affecting one in six men during their lifetime. More than 2 million men in the U.S. and 16 million men worldwide are prostate cancer survivors.

"At present we lack an understanding of risk factors that can be changed or controlled to lower the risk of lethal prostate cancer. 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 lead author Kathryn Wilson, a research fellow in epidemiology at HSPH.

The researchers chose to study coffee because it contains many beneficial compounds that act as antioxidants, reduce inflammation, and regulate insulin, all of which may influence prostate cancer. Coffee has been associated in prior studies with a lower risk of Parkinson's disease, type 2 diabetes, gallstone disease, and liver cancer or cirrhosis.

The study examined the association between coffee consumption and the risk of prostate cancer, particularly the risk for aggressive prostate cancer among 47,911 U.S. men in the Health Professionals Follow-Up Study who reported their coffee consumption every four years from 1986 to 2008. During the study period, 5,035 cases of prostate cancer were reported, including 642 fatal or metastatic cases.

Among the findings:

• Men who consumed the most coffee (six or more cups daily) had nearly a 20% lower risk of developing any form of prostate cancer.
• The inverse association with coffee was even stronger for aggressive prostate cancer. Men who drank the most coffee had a 60% lower risk of developing lethal prostate cancer.
• The reduction in risk was seen whether the men drank decaffeinated or regular coffee, and does not appear to be due to caffeine.
• Even drinking one to three cups of coffee per day was associated with a 30% lower risk of lethal prostate cancer.
• Coffee drinkers were more likely to smoke and less likely to exercise, behaviors that may increase advanced prostate cancer risk. These and other lifestyle factors were controlled for in the study and coffee still was associated with a lower risk.

The results from this study need to be validated in additional populations that have a range of coffee exposure and a large number of lethal prostate cancer cases. If confirmed, the data would add to the list of other potential health benefits of coffee. The authors currently are planning additional studies to understand specific mechanisms by which coffee may specifically lower the risk of lethal prostate cancer.

For more information on the Harvard School of Public Health, visit http://www.hsph.harvard.edu/