For the study, Wilson's team collected data on almost 48,000 men who took part in the Health Professionals Follow-Up Study and followed them until 2008. Every four years from 1986 on these men reported on how much coffee they drank.
The researchers then calculated the risk for prostate cancer tied to the amount of coffee consumed. During the period of the study, they identified 5,035 cases of prostate cancer, of which 642 were fatal cases in which the cancer was metastatic, meaning that it had spread beyond the original site.
The Harvard team found that drinking six or more cups of coffee each day was associated with an almost 20 percent lower risk of developing prostate cancer, compared to those who did not drink coffee.
In addition, the odds of developing a more lethal or advanced prostate cancer dropped by 60 percent, compared to men who abstained from coffee -- a statistically significant and "substantially lower" relative risk, according to the researchers.
Even men who drank less coffee -- one to three cups a day -- had a 30 percent lower risk of developing lethal prostate cancer, and reductions in risk were observed whether the men drank caffeinated or decaffeinated coffee, Wilson's group added.
After taking into account other lifestyle factors, such as age, smoking, obesity and exercise, the decline in the odds for prostate cancer remained, they said.
"This adds to the evidence from a variety of diseases that coffee doesn't seem to be harmful," Wilson said. "It has been shown, pretty consistently, to be associated with lower risk of Parkinson disease, type 2 diabetes and liver cancer. This is another potential plus for coffee."
The study was limited by self-reported data and the lack of data on coffee intake from earlier periods of the men's lives, the researchers noted.
The finding comes on the heels of a study published last week that fou
All rights reserved