From Scientific American:
Researchers from Tokyo’s National Cancer Center studied data from more than 96,000 men and women aged between 40-69 over a period of up to 12 years from 1990, a member of the team said on Wednesday. They found no significant benefit in men. Even after adjusting for other factors including diet and exercise, they found that women who drank three or more cups of coffee a day had half the risk of developing colon cancer, compared with those who drank no coffee at all. The researchers, whose findings have been published in the International Journal of Cancer, did not find any link between consumption of green tea and colon cancer.