A long-term study of almost 50,000 US men found those who drank six or more cups of coffee a day were less likely to develop a lethal form of prostate cancer, the most common cancer in men, but non-drinkers should not rush to take up the habit.
The study, reported this week in the Journal of the National Cancer Institute, followed 47,911 US men during a 20-year period between 1986 and 2006. Every four years the men reported their average daily coffee intake and findings show men who consumed six or more cups daily had an almost 20 percent lower risk of contracting any form of prostate cancer.
“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 Kathryn Wilson, lead author of the report and a research fellow at the Harvard School of Public Health (HSPH).
Lethal prostate cancer causes death or spreads to the bones.
Coffee had an even stronger association with aggressive prostate cancer and men who consumed the greatest amount of coffee had a 60 percent lower risk of developing lethal prostate cancer, the study shows. Even drinking one to three cups of coffee per day was linked to a 30 percent lower risk of contracting lethal prostate cancer.
During the study period, 5,035 cases of prostate cancer were reported, including 643 fatal or metastatic cases.
The study also found caffeine does not appear to be a factor, as the risk reductions were found in men who drank regular or decaffeinated coffee.
Coffee drinkers are also more likely to be smokers and less likely to exercise, factors that could lead to advanced prostate cancer risk. These and additional lifestyle factors were a part of the control group and coffee was still associated with lower risk.
“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.
Coffee was chosen for the study because of the many beneficial compounds it is known to contain helping act as oxidants, reducing inflammation, and regulating insulin, all influencing prostate cancer. Previous studies have also shown coffee consumption is associated with a lower risk of Parkinson’s disease, type 2 diabetes, liver cancer or cirrhosis, and gallstone disease, the authors note.
Prostate cancer, the second leading cause of cancer death for men in the US and the most critical to prevent, is the most frequently diagnosed form of cancer and impacts one in six men during their lifetime. In the US, more than 2 million men are prostate cancer survivors. Worldwide, the number of survivors is 16 million, according to the study’s authors.
The authors have called for a validation of the study in additional populations having a range of coffee exposure and a high number of lethal prostate cancer cases. They note if the results are confirmed, the data would then show the additional benefits of coffee.
Dr. Helen Rippon of The Prostate Cancer Charity, said: men who are not already coffee drinkers should not rush out for the caffeine buzz, noting the evidence is still unclear. “Although this study is a welcome addition to our knowledge, it is far from definitive and we would not recommend men who are not already habitual coffee drinkers to become so in the hope of preventing prostate cancer,” she said, according to the BBC.