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Effects of alcohol consumption on risk of colorectal cancer; potential modification by folate intake

Critique 149: The association of alcohol consumption with the risk of death from colorectal cancer – 28 October 2014 Data from prospective cohort studies on the association between alcohol consumption and the occurrence of colorectal cancer (CRC) are conflicting, with some suggesting an increase in risk while others failing to show such an effect. There are little data on the effects of alcohol consumption on the risk of mortality from CRC. The present study is based on a meta-analysis of data from nine cohort studies (with a total of more than two million subjects) to judge how the level of alcohol intake relates to CRC mortality. A total of almost 4,000 deaths from CRC were recorded. The conclusions of the authors are that the consumption of ≥ 50 grams of alcohol (about 4 typical drinks or more) per day increases the risk of death from CRC modestly [RR 1.21 (95% CI 1.01, 1.46)], but “light” drinking (≤ 12.5 g/day) or “moderate” drinking (12.6-49.9 g/day) do not increase the risk of CRC death. In fact, they state that their data support a “J-shaped” relation between alcohol intake and CRC mortality (i.e., a slight decrease in mortality associated with light drinking but an increased risk with heavier drinking). Forum members considered this to be a well-done analysis. They noted the inability of the authors to evaluate differences in effect according to type of beverage consumed, the pattern of drinking, or the underlying folate levels of subject, all of which probably modify such a relation. The results are in line with earlier reports on alcohol and breast cancer, where alcohol appears to increase the incidence of the disease but does not increase mortality. For most diseases, including colorectal cancer, there may a J-shaped effect on mortality: a reduction in risk for light-to-moderate drinking but an increase with heavier drinking. Overall, the present meta-analysis supports a finding of increased risk of death from colorectal cancer from heavy drinking. However, it shows rather convincingly that light to moderate amounts of alcohol do not increase the risk of death from this disease, probably because of the protective effects of moderate drinking on cardiovascular disease, a more common cause of mortality.

Reference: Cai S, Li Y, Ding Y, Chen K, Jin M. Alcohol drinking and the risk of colorectal cancer death: a meta-analysis. European Journal of Cancer Prevention 2014;23:532–539.

For the full critique of this paper by members of the International Scientific Forum on Alcohol Research, please click here.
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