COLORECTAL CANCER
Colorectal cancer is currently one of the most common
cancers worldwide. For decades, the relationship
between coffee consumption and the risk for colorectal
cancer has been extensively examined. Some studies
published in the 80s reported an adverse association
between coffee consumption and colon cancer among
people consuming ≥2 cups of coffee a day [38], whereas
others did not show any relationship or suggest
a beneficial effect of coffee on colorectal cancer risk
[33]. Nevertheless, all studies emphasized that more
data are needed in order to determine the exact nature
of the relationship, if any, between coffee consumption
and cancer risk.
Numerous case-control and cohort studies have
been published since the 80s. In 1991, a Working Group
of the International Agency for Research on Cancer
reviewed the existing data and concluded that there is
some evidence of an inverse relation between coffee
drinking and cancer of the large bowel in man [10].
This suggestion was later confirmed in a meta-analysis
of case-control studies based on data published up to
1997 [12]. Numerous meta-analyses have been undertaken
recently and their results are also optimistic. A
meta-analysis of prospective cohort studies in 2009
showed no significant effect of coffee consumption on
colorectal cancer risk [16], whereas a meta-analysis of
case-control studies in 2010 suggested a moderately
favorable effect (17% lower risk of cancer) [10]. A beneficial
effect of coffee on the risk of colorectal cancer
was also confirmed by a meta-analysis of cohort studies
in 2011 [52]. As many as three analyses and a review
of data were published in 2013. One of them, including
case-control studies, stated that the risk of colorectal
cancer is reduced by 15% for heavy coffee drinkers as
compared to low or non-drinkers, and that the risk of