Alcohol Linked to Colorectal Cancer Risk

Emma Hitt, PhD

September 18, 2011

September 18, 2011 — Alcohol consumption appears to be strongly and dose-dependently linked to colorectal cancer risk, according to the findings of a new meta-analysis.

Veronika Fedirko, PhD, with the International Agency for Research on Cancer, in Lyon, France, and colleagues reported their findings in the September issue of the Annals of Oncology.

According to the researchers, several studies have suggested a link between alcohol consumption and colorectal cancer risk. However, "precise quantification of the association for light and/or moderate alcohol consumption and the identification of a possible threshold of effect remain to be determined." In addition, further information is needed on the "potential heterogeneity of effects by sex, colorectal site, and geographical region."

The current study included 27 cohort and 34 case-control studies published before May 2010 that reported results for at least 3 categories of alcohol intake.

Moderate alcohol consumption was associated with a 21% increase in colorectal cancer (relative risk [RR], 1.21; 95% confidence interval [CI], 1.13 - 1.28), whereas heavy drinking (≥ 4 drinks/day) was associated with a 52% increased risk (RR, 1.52; 95% CI, 1.27 - 1.81).

Compared with nondrinkers and occasional drinkers, men who drank moderate amounts of alcohol (RR, 1.24; 95% CI, 1.13 - 1.37) were more at risk than women who drank similar amounts (RR, 1.08; 95% CI, 1.03 - 1.13).

In addition, Asians were more at risk if they were heavy drinkers than were other ethnicities. The researchers state that this finding may be due in part to a high prevalence of the slow-metabolizing variant of aldehyde dehydrogenase enzyme, present among Asians.

Overall, the dose-risk analysis found a statistically significant 7% increased risk for colorectal cancer for 10 g per day of alcohol intake, which includes light alcohol consumers. According to the researchers, 1 drink is equivalent to 12 g of ethanol.

"The results from this large meta-analysis have important public health implications, given the large number of women and, especially, men consuming alcohol and the high incidence of colorectal cancer worldwide and in developed countries in particular," Dr. Fedirko and colleagues conclude.

No potential explanation was given by the researchers for a mechanism that could explain the association between alcohol consumption and colorectal cancer. In addition, the study authors note that they did not examine whether the "association of alcohol with colorectal cancer risk varied by folate status, smoking, or other potential modifying factors because very few studies investigated these associations."

This study was supported by the International Agency for Research on Cancer, the Italian Association for Research on Cancer, and the Italian Foundation for Cancer Research. The study authors have disclosed no relevant financial relationships.

Ann Oncol. 2011;22:1958-1972.

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