Daily Archives: 14/10/2015

Light to moderate intake of alcohol, drinking patterns, and risk of cancer

This was some new research published in the BMJ in August looking at two large US cohorts.  I’ve shared the abstract and key points below:

cancer and moderate drinking

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; Ptrend=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; Ptrend=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 (Ptrend=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.

Potential mechanisms

Acetaldehyde, the first and most toxic ethanol metabolite, is considered a cancer causing agent.32 Ethanol could also stimulate carcinogenesis by inhibiting DNA methylation and interacting with retinoid metabolism. Bacterial microbiota contributes to the metabolism of alcohol and could mediate many disease promoting and genotoxic effects of alcohol,33 in particular for colorectal cancer,34 as well as cancers of the oral cavity, where saliva acetaldehyde was found to be high for increasing ethanol intake and where further metabolism of acetaldehyde is limited.35 Breast tissue might be more susceptible to alcohol than other organs. Probable explanations involve increased estrogen and androgen levels.30 36

What is already known on this topic

  • Heavy alcohol consumption has been linked to an increased risk of several cancers

  • However, the association between light to moderate drinking and overall cancer risk is less clear in US women and men, among whom light to moderate drinking is prevalent

  • Furthermore, the role of alcohol independent of smoking is unclear. In studies that include smokers, the apparent influence of alcohol on cancer could be partly driven by its effect among smokers; thus, findings might not be generalizable to non-smokers, who now comprise the majority of the US population

What this study adds

  • Light to moderate drinking (<15 and <30 g of alcohol per day for women and men, respectively) was associated with minimally increased risk of overall cancer in both women and men

  • Risk of alcohol related cancer is not appreciably increased for light to moderate drinking men (up to two drinks per day) who have never smoked

  • But in women who have never smoked, the risk of alcohol related cancer (mainly breast cancer) increases even within the range up to one alcoholic drink a day

This is over 120,000 participants so a good size study and featured in the BMJ a very prestigious medical journal.  So my take away from the findings is as a woman that drinking is a really bad idea, and drinking and smoking is a terrible idea as relates to breast cancer risk …….