Coffee May Ward off Lethal Prostate Cancer

A growing body of research is showing that coffee drinking poses little to no health risk for most people. In a new large-scale study, researchers have found that coffee may lower the risk of lethal prostate cancer.

Coffee contains a diverse mix of biologically active compounds, some of which are thought to protect DNA from damage that can contribute to cancer. Teasing out the cumulative effects off all these compounds in the human body can be difficult. Heavy coffee drinking sometimes goes hand in hand with unhealthy habits, like smoking and a less active lifestyle, and it’s difficult to separate the effects of coffee from these other factors.

A team of researchers led by Drs. Kathryn Wilson and Lorelei Mucci at the Harvard School of Public Health set out to investigate whether coffee intake affects the risk for prostate cancer. The prostate is a gland in the male reproductive system found below the bladder and in front of the rectum. Prostate cancer usually occurs in older men. In 2010, there were over 200,000 new cases nationwide and over 32,000 deaths from the disease. Results from previous studies looking into the effects of coffee on prostate cancer were inconsistent due to their small size and confounding factors such as smoking.

The researchers examined data from the Health Professionals Follow-up Study, which was funded by NIH’s National Cancer Institute (NCI). Coffee intake was assessed in 1986 for the almost 48,000 men who made up the study and then every 4 years thereafter. By 2006, over 5,000 patients with prostate cancer were identified, including 642 with lethal cancers (those that caused death or advanced cancer that had spread to bone). The scientists adjusted for other variables like smoking and obesity. Their results appeared on May 17, 2011, in the online edition of the Journal of the National Cancer Institute.

The researchers estimated that men who had 6 or more cups of coffee per day had an 18% lower risk for overall prostate cancer than those who didn’t drink coffee. The association was even stronger for lethal prostate cancer. Those who drank 6 or more cups per day had an estimated 60% lower risk for lethal prostate cancers than those who didn’t drink coffee. Coffee consumption wasn’t associated with the risk of non-advanced or low-grade cancers.

The association with lethal cancer was similar for regular and decaffeinated coffee, so caffeine doesn’t appear to play a role. The authors are now planning experiments to explore the mechanisms by which coffee might have this effect.

If coffee drinking is confirmed to lower risk of prostate cancer, it will add to the evidence showing that simple dietary changes can make a big impact in the fight against cancer. The coffee drinkers in this study were more likely to smoke and less likely to engage in vigorous exercise — other behaviors known to raise the risk for prostate cancer. Nevertheless, factors the researchers didn’t consider may also have affected the results.

“At present we lack an understanding of risk factors that can be changed or controlled to lower the risk of lethal prostate cancer,” Wilson says. “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.”

— by Harrison Wein, Ph.D.