Attributing lifestyle factors to the risk of developing colorectal (CRC) cancer remains largely controversial. Alcohol consumption, obesity, diet high in animal fat and smoking have all been identified as risk factors, yet the exact threat of risk has been inconsistent in the literature. Nonetheless alcohol is one of the most avoidable factors. To that end, Fedirko and colleagues conducted a meta-analysis for any light, moderate and heavy drinking and dose-risk meta-regression analysis of observational studies published prior to May 2010 on alcohol consumption and colorectal cancer.1
Fifty-seven published studies on CRC incidence and alcohol intake between 1986 and 2010 were identified. The summary relative risks (RRs) were estimated by the random effects model. Second-order fractional polynomials and random effects meta-regression models were used for modeling the dose-risk relation. Nondrinkers or occasional drinkers were the reference category. Light alcohol drinking was defined as consumption of =1 drink/day (=12.5g/day of ethanol), moderate as 2-3 drinks/day (12.6-49.9g/day of ethanol) and heavy as =4 drinks/day (=50g/day 0f ethanol). The author’s findings include:1
- RRs were higher for rectal than for colon cancer among any drinkers (P = 0.03) and light drinkers (P = 0.05) but about the same in moderate and heavy drinkers
- Men had a statistically significantly higher risk than women among any drinkers (P = 0.001) and moderate drinkers (P = 0.02)
- A possible heterogenecity by geographical location was observed only in heavy drinkers (P = 0.04) with the highest risk summary estimate of 1.81 (95% CI 1.33-2.46) for studies conducted in Asia and the lowest risk summary estimate of 1.16 (95% CI 0.95-1.43) for studies conducted in Europe
- RRs for of CRC were 1.08 (95% CI 1.03-1.13) and 1.24 (95% CI 1.13-1.37) for women and men respectively, for moderate alcohol consumption, compared with nondrinkers
- RR for heavy drinking was 1.52 (95% CI 1.27-1.81), compared with nondrinkers or occasional drinkers
- Dose-risk analysis estimated RRs of 1.07 (95% CI 1.04-2.20), 1.38 (95% CI 1.28-1.50), and 1.82 (95% CI 1.41-2.35) for 10, 50 and 100g/day of alcohol respectively
The results of this meta-analysis provide strong evidence for the association between alcohol consumption of > 1 drink/day and CRC risk. Thus the authors suggest that public health considerations toward CRC prevention should include limiting intake of alcoholic beverages.
Alcohol consumption is one of the largest avoidable/modifiable risk factors for cancer. It is an attributable risk for head and neck, esophageal, liver, female breast cancer and CRC.2 As such; it possibly could earn the label “carcinogenic in humans.” However based on the findings of this meta-analysis specific to CRC, as with other risk factors adapted in lifestyle choices, it seems as though moderation remains the key to a healthy lifestyle and minimization of controllable risk for development of CRC.
Fedirko V, Tramacere I, Bagnardi V, et al. Alcohol drinking and colorectal cancer risk: An overall and dose-response meta-analysis of published studies. Ann of Oncol. 2011; Feb 9 [Epub ahead of print]. doi:10.1093/annonc/mdq653 Link to abstract http://www.ncbi.nlm.nih.gov/pubmed/21307158
- Baan R, Straif K, Grosse Y, et al. Carcinogenicity of alcoholic beverages. Lancet Oncol. 2007; 8(4): 292-293. doi:10.1016/S1470-2045(07)70099-2 Link to full text (registration required) http://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(07)70099-2/fulltext#