Alcohol Consumption and the Risk of Colorectal Cancer

Researchers conducted a meta-analysis of 16 studies to explore the relationship between alcohol consumption and invasive colorectal cancer (CRC). Overall, the studies included 4,276 CRC cases and 15,802 controls from 5 case-control and 11 nested case-control studies. The authors used only the average level of alcohol intake and did not have data on drinking patterns or type of beverage. The sample consisted of: 41% people with no alcohol consumption (including people who formerly consumed alcohol and those who never had); 47% reporting an average consumption of 1.1 to 28 g alcohol/day; 6% reporting 28.1 to 42 g/day; and 6% reporting >42 g/day.

• Results showed a significant J-shaped curve across multiple spline and restricted cubic‐spline models; there was an 8% reduction in risk of CRC for people who consumed up to 28 g/day (about 2 drinks/day), and a 25% increased risk for people reporting an average of >42 g/day (about 3 or more drinks/day).
• Results did not vary by age, obesity, smoking, or family history of CRC.

Comments: Despite the inability to judge the effects of drinking pattern (heavy episodic versus “moderate”) or type of beverage—and the inclusion of people who formerly consumed alcohol in the non-drinking category—these results suggest a J-shaped curve for the relation of alcohol intake to CRC. It is possible that the results would have been different if additional factors had been considered, including social determinants (for which it is difficult to control) that may skew otherwise linear associations between alcohol and risk of cancer towards the J-shaped curve.

R. Curtis Ellison, MD

Reference: McNabb S, Harrison TA, Albanes D, et al. Meta-analysis of 16 studies of the association of alcohol with colorectal cancer. Int J Cancer. 2019 [Epub ahead of print]. doi: 10.1002/ijc.32377.