Alcohol and Breast Cancer: What to Tell Your PatientsOctober 23, 2018 /
Anne Danahy, MS, RDN
Breast cancer is the second most common cancer among women. Data from the National Cancer Institute indicates that there are more than 3.4 million women in the United States who are living with breast cancer.1 However, many questions still exist about the risk factors, especially those that are modifiable. One risk factor that researchers have established, with some debate, is that drinking alcohol increases a woman’s risk for breast cancer. Ideally, no alcohol is best, but what should registered dietitians (RDs) tell patients who are worried about their risk but also find zero tolerance to be a bit intolerable?
The Impact of Alcohol on Risk
Two important cancer research agencies, the American Institute for Cancer Research (AICR) and the International Agency for Research on Cancer (IARC)—a division of the World Health Organization—have stated that there is convincing evidence that alcohol consumption increases the risk for cancer.2 Studies show that although heavy drinkers are at the greatest risk, even light drinkers are at a slightly higher risk for breast cancer than nondrinkers.2 For every 10 g of ethanol consumed per day, the risk of breast cancer increases by 5% in premenopausal women and 9% in postmenopausal women.2 For reference, a standard drink (5 oz of wine, 1.5 oz of distilled spirits, or 12 oz of regular beer) contains approximately 14 g of ethanol.2
How Does Alcohol Increase the Risk?
Alcohol promotes hormonal changes by increasing aromatase activity.3,4 Aromatase is an enzyme that converts androgen hormones to estrogen. It also triggers the expression of hormone receptors in the breast. More circulating estrogen and more receptors to bind to increases the risk of estrogen receptor positive breast cancer.
Alcohol also stimulates cell proliferation, which means that cancer cells can divide and spread faster. It also stimulates the insulin-like growth factor axis, which speeds the growth of epithelial cells in the breast. This leads to increased amounts of dense breast tissue—another suspected risk factor.5
In addition to its hormonal effects, ethanol is carcinogenic and damages DNA. A common question among consumers is whether all types of alcohol confer the same risk. Epidemiological studies suggest that ethanol is the major culprit, but some alcoholic drinks might pose an additional risk. Along with ethanol, distilled spirits contain other carcinogenic compounds such as acetaldehyde and nitrosamines, which can provide an addictive effect.3 On the flip side, red wine contains phytochemicals. In lab studies, phytochemicals have been shown to inhibit aromatase activity and protect DNA in cells that have been exposed to ethanol.3
Alcohol also interferes with folate absorption and metabolism. Because folate is involved in the synthesis, repair, and methylation of DNA, researchers suspect that this may be another possible mechanism for the increased risk among alcohol drinkers. Among younger, premenopausal women, de Batlle et al found that high alcohol consumption and low intake of dietary folate were associated with an increased risk of breast cancer, and that diets high in folate appeared to be protective among women who were heavier drinkers.5 While a study conducted by Kim et al. did not find an association between alcohol consumption and breast cancer risk overall, their findings showed that younger women with a family history of breast cancer and low folate intake (less than 400 μg/day) combined with high alcohol intake had an increased risk of breast cancer.6
The Bottom Line – What To Advise Patients
Based on the research and recent statements from AICR and IARC, patients who are willing to abstain from alcohol to modify their risk should certainly be encouraged to do so. However, many others may have a harder time with this. For those patients, it is important to stress moderation and work on strategies that can offset the risk associated with alcohol.
A study by Schutze et al. found that the total percent of alcohol-related breast cancer cases in 8 European countries was only 5%.7 For women who are reluctant to abstain, RDs should review the research and stress the recommendation to stick to 1 drink per day or less. In addition, red wine might be the best and safest choice for an alcoholic beverage.
All women, especially those who are heavier drinkers, should work on consistently incorporating more fruits, leafy green vegetables, legumes, and other sources of folate into their diet. These foods are also rich in antioxidants and fiber, which can provide additional protection. Finally, women should be aware that being overweight, especially if metabolic disease develops, is probably an even greater risk for breast cancer. A combination of more plant foods, and less alcohol can likely help to reduce weight, and have the greatest impact on reducing breast cancer risk.
- Cancer stat facts: Female breast cancer. National Cancer Institute. https://seer.cancer.gov/statfacts/html/breast.html. Accessed October 10, 2018.
- LoConte NK, Brewster AM, Kaur JS, Merrill JK, Alberg AJ. Alcohol and cancer: a statement of the American Society of Clinical Oncology. J Clin Oncol. 2018;36(1):83-93.
- Scoccianti C, Lauby-Secretan B, Bello PY, Chajes V, Romieu I. Female breast cancer and alcohol consumption: a review of the literature. Am J Prev Med. 2014;46(3):S16-25.
- Ziembicki S, Zhu J, Tse E, Martin LJ, Minkin S, Boyd NF. The association between alcohol consumption and breast density: a systematic review and meta-analysis. Cancer Epidemiol Biomarkers Prev. 2017;26(2):170-8.
- de Batlle J, Ferrari P, Chajes V, et al. Dietary folate intake and breast cancer risk: European prospective investigation into cancer and nutrition. J Natl Cancer Inst. 2015;107(1):367.
- Kim HJ, Jung S, Eliassen AH, Chen WY, Willett WC, Cho E. Alcohol consumption and breast cancer risk in younger women according to family history of breast cancer and folate intake. Am J Epidemiol. 2017;186(5):524-31.
- Schütze M, Boeing H, Pischon T, et al. Alcohol attributable burden of incidence of cancer in eight European countries based on results from prospective cohort study. BMJ. 2011;342:d1584.