Light Alcohol Drinking and Risk of Cancer: A Meta-Analysis of Cohort Studies.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational cohort studies
PubMed 28546524 · doi:10.4143/crt.2017.094
What was done
A systematic review and random-effects meta-analysis of cohort studies indexed in PubMed and EMBASE (searched April 2016) evaluating cancer incidence and mortality associated with very light (≤0.5 drink/day), light (≤1 drink/day), and moderate (1–2 drinks/day) alcohol consumption.
What was found
Across 60 cohort studies from 135 articles, very light or light drinking was not associated with the incidence of most cancers. However, light drinking was associated with a statistically significant increase in female breast cancer and male colorectal cancer, alongside a significant decrease in lung cancer and a marginally significant decrease in thyroid cancer across both sexes. Moderate drinking was associated with increased female breast and male colorectal cancer incidence, and decreased incidence of hematologic malignancies in both sexes. The abstract reports no numerical relative risks or confidence intervals.
Why it matters
This meta-analysis refines broad public health generalizations about alcohol carcinogenicity by showing that at light drinking levels (≤1 drink/day), elevated risks appear specific to female breast and male colorectal cancers rather than applying across all cancer types.
Limits
Total participant count, specific pooled effect sizes, and confidence intervals are not reported in the abstract. Because the meta-analysis includes only observational cohort studies, results remain vulnerable to confounding (such as smoking), misclassification bias from self-reported alcohol intake, and reference-group biases.
Cited by
- supports Very light alcohol drinking (less than half a standard drink per day or under 5 drinks per week) increases the relative risk of breast cancer by around 4%, shifting baseline lifetime risk from 1 in 8 to about 1 in 7.7.