Alcohol and Cancer - with focus on low doses

Alcohol drinking is strongly related to upper digestive and respiratory tract neoplasms, and – to a lesser degree – to cancers of the colorectum, liver, breast and, for heavy drinking, stomach and pancreas. Quantification of the association between low doses of alcohol consumption and cancers known to be alcohol-related is important. Data on moderate alcohol drinking, defined as 1 or less drink/day, were derived from meta-analyses or collaborative re-analyses of selected alcohol-related cancers. For oral and pharyngeal cancer, an increased risk is present at low doses of consumption. The pooled relative risk (RR) of oral and pharyngeal cancer was 1.21 (95% CI, 1.10-1.33) for 1 or less drink/day vs. non/occasional drinkers. For esophageal squamous cell carcinoma, the summary RRs for light drinking were 1.31 (95% CI, 1.10-1.57) for the overall analysis, based on 26 studies, and 1.35 (95% CI, 0.92-1.98) for cohort studies alone (8 studies). When the analysis was stratified by geographical area, the association was stronger in Asia (RR 1.63), indicating a potential effect modification by genetic susceptibility. Laryngeal cancer was not associated with light alcohol consumption 7. The summary RR for light drinking, based on 10 case-control and 2 prospective studies, was 0.88. Almost 50 studies provided information on low doses of alcohol and colorectal cancer risk. No overall association was reported with colorectal (RR=1.00; 95% CI, 0.95-1.05), colon (RR=0.96; 95% CI, 0.90-1.02) nor rectal (RR=1.06; 95% CI, 0.98-1.14) cancers. The meta-analysis on alcohol and pancreatic cancer considered moderate alcohol consumption, defined as less than 3 drinks/day, and found strong evidence for a lack of positive association at low to moderate intakes: the summary RR was 0.92 (95% CI, 2 0.86-0.97). Likewise, there was no association between moderate drinking and stomach cancer in an individual data pooled analysis (StoP). In the collaborative reanalysis on breast cancer, the RRs were 1.01 (p>0.05) for women reporting alcohol consumption <5 g/day and 1.03 (p>0.05) for those consuming 5-14 g/day. The Million Women Study found a RRs 1.08 (p<0.05) for 3-6 drinks/week (i.e., around 4 to 8 g/day), compared to non-drinkers. In terms of attributable fraction of cancers, reducing of alcohol drinking to the limits indicated by the European Code Against Cancer (20 g/day for men and 10 g/day for women) would avoid about 90% of alcohol-related cancers and cancer deaths in men and over 50% of cancers in women. Avoidance, or moderation, of alcohol consumption is therefore a global priority for cancer prevention.