Light to moderate intake of alcohol, drinking patterns, and risk of cancer: results from two prospective US cohort studies

Abstract

Objectives: To quantify risk of overall cancer across all levels of alcohol consumption among women and men separately, with a focus on light to moderate drinking and never smokers; and assess the influence of drinking patterns on overall cancer risk.

Design: Two prospective cohort studies.

Setting: Health professionals in the United States.

Participants: 88,084 women and 47,881 men participating in the Nurses' Health Study (from 1980) and Health Professionals Follow-up Study (from 1986), followed until 2010.

Main outcomes and measures: Relative risks of cancer.

Results: 19,269 and 7571 (excluding non-advanced prostate cancers) incident cancers were documented among women and men, respectively, over 3,144,853 person years. Compared with non-drinkers, light to moderate drinkers had relative risks of total cancer of 1.02 (95% confidence interval 0.98 to 1.06) and 1.04 (1.00 to 1.09; P(trend) = 0.12) for alcohol intake of 0.1-4.9 and 5-14.9 g/day among women, respectively. Corresponding values for men were 1.03 (0.96 to 1.11), 1.05 (0.97 to 1.12), and 1.06 (0.98 to 1.15; P(trend) = 0.31) for alcohol intake of 0.1-4.9, 5-14.9, and 15-29.9 g/day, respectively. Associations for light to moderate drinking and total cancer were similar among ever or never smokers, although alcohol consumption above moderate levels (in particular ≥ 30 g/day) was more strongly associated with risk of total cancer among ever smokers than never smokers. For a priori defined alcohol related cancers in men, risk was not appreciably increased for light and moderate drinkers who never smoked (P(trend) = 0.18). However, for women, even an alcohol consumption of 5-14.9 g/day was associated with increased risk of alcohol related cancer (relative risk 1.13 (95% confidence interval 1.06 to 1.20)), driven by breast cancer. More frequent and heavy episodic drinking was not further associated with risk of total cancer after adjusting for total alcohol intake.

Conclusion: Light to moderate drinking is associated with minimally increased risk of overall cancer. For men who have never smoked, risk of alcohol related cancers is not appreciably increased for light and moderate drinking (up to two drinks per day). However, for women who have never smoked, risk of alcohol related cancers (mainly breast cancer) increases even within the range of up to one alcoholic drink a day.

Conflict of interest statement

Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: no support from any organization for the submitted work; no financial relationships with any organizations that might have an interest in the submitted work in the previous three years; and no other relationships or activities that could appear to have influenced the submitted work.

© Cao et al 2015.

Figures

Fig 1 Non-parametric regression curves showing the association between alcohol consumption and risk of cancer (total and alcohol related). Blue lines=relative risk; dotted lines=95% confidence intervals

Fig 2 Risk of total and alcohol related cancer jointly by alcohol consumption and smoking history