A review of studies published in the International Journal of Cancer indicated that "coffee is not significantly associated with a decreased risk of colorectal, colon, or rectal cancer, contrary to the results of previous trials that found a possible protective effect of coffee against these cancers."

"An inverse association between coffee consumption and the risk of colorectal cancer has been found in several case-control studies," According to Dr. Youjin Je, of Harvard School of Public Health, Boston, "but the association was not consistent in prospective cohort studies, which are designed differently."

A systematic review of prospective cohort studies to examine the association between coffee consumption and colorectal cancer was undertaken by the researchers. They identified 12 studies that included a total of 646,848 participants and 5,403 patients with colorectal cancer.

"The combined result of the studies, comparing high versus low coffee consumption categories, revealed no significant association between coffee consumption and colorectal cancer risk," researchers found. "Overall, there were no significant differences by sex and cancer site. However, there was a slight inverse association between coffee consumption and colon cancer in women who had a 21% reduced risk. This was especially true among Japanese women who had a 38% reduced risk.