Alcohol consumption before pregnancy and breast cancer, a challenging concern

When I have lectured about toxicology in high school or college classrooms, I have always found it valuable to present examples of ‘toxicants’ or ‘environmental exposures’ that are relevant to the students. Often times I have found that if I come into a classroom and ask the students what they think about when I say, “environmental exposures”, they respond, “Wind! Sun!” etc., and I use this first step as a platform to try and discuss how our ‘environment’ can include the air we breathe, the food we eat, medications we take, and any chemical that we may be exposed to. Looking for examples, I like to ask students about their impressions on the toxicities of certain examples, such as coffee or Tylenol. When I have given the toxicology lectures for the freshman Environmental Health class at the University of Washington, bringing up alcohol is always a topic that immediately gains the attention of the students.

Heavy alcohol consumption has clear toxicologic implications. Acute alcohol poisoning can result in overwhelming nervous system depression leading to respiratory failure, while chronic heavy alcohol consumption is largely dangerous due to repeated liver injury and progression into liver cirrhosis, where liver failure occurs as healthy hepatocytes are replaced with extensive fibrosis. Now we can all agree that heavy alcohol consumption is dangerous and should be avoided, but, as with many questions in toxicology, the question of lower level exposures, or moderate drinking, requires further investigation.

As I was browsing the Health section of the New York Times, I came across this headline:

http://well.blogs.nytimes.com/2013/09/06/drinking-when-young-increases-breast-cancer-risk/

This brief article brought attention to a recent article published in the Journal of the National Cancer Institute, from the Washington University in St. Louis, MO.

http://jnci.oxfordjournals.org/content/early/2013/08/24/jnci.djt213.full.pdf+html

In this study, the authors analyze the data collected from the Nurses’ Health Study II (NHSII) cohort, where roughly 115,000 female registered nurses completed questionnaires biennially from 1989 to 2003 answering numerous questions about their lifestyle and health status, including alcohol consumption at different points in their lives. From these surveys, they addressed the relationship between alcohol consumption prior to first pregnancy and the risk of developing overt breast cancer or benign breast disease. Although alcohol has been suggested to be associated to women’s risk of developing breast cancer for some time, this study was unique in that it addressed alcohol consumption rates for women between the ages of 15 and 40, asking the question of whether or not alcohol consumption between menarche and first pregnancy influences risk of developing breast cancer later in life. Their observations were that women’s alcohol consumption in this time period was positively associated with incidence of breast cancer, where an alcohol consumption rate of 10 g/day (roughly a glass of wine a day) between menarche and first pregnancy was associated with an 11% increase in risk of breast cancer, with continued alcohol consumption after first pregnancy to have less of an effect. This data would suggest that if this trend were linear, a 20 g/day alcohol consumption rate (2 glasses of wine a day) would give over a 20% increase in risk of breast cancer.

These are concerning observations. It is particularly concerning to me that they observed the risk of developing breast cancer increases when the time between menarche and first pregnancy is greater. As the age of menarche in women is continuing to decrease (potentially being driven from environmental factors including, endocrine disruptors) and the age of first pregnancy is continuing to increase (economic and social pressures), this length of time is becoming greater, further influencing population level risk of developing breast cancer.

The authors’ conclude that eliminating or reducing alcohol consumption may be an effective mechanism to reduce cancer risk.

Now, although this is likely to be true, unfortunately breast cancer is not the only disease women are at risk to suffer from. Cardiovascular disease continues to remain the greatest cause of disease in the Western world, and there is strong evidence that moderate alcohol consumption reduces risk of cardiovascular disease and stroke.

In a 2009 article in JAMA, moderate alcohol consumption (described at 5-14 drinks per week, or roughly 7 – 20 g/day) was independently associated with a reduced risk of heart failure in men.

http://jama.jamanetwork.com/article.aspx?articleid=184310

In what is probably the stronger association, moderate alcohol consumption provides a significant reduction in stroke, providing a benefit or no adverse risk in women with alcohol consumption up to 40 g/day (roughly 4 glasses of wine/day), with greater than 40 g/day increasing risk of stroke. Similar benefits were also observe in men.

http://jama.jamanetwork.com/article.aspx?articleid=195880

In addition, consumption of alcohol was found to be associated with a reduced risk of dementia in older adults. In this prospective study, consumption of 1-6 drinks/week was associated with a reduced incident demetia risk in both men and women. Upon stratification of the sexes, women who consumed 7-13 drinks/week appeared to have an even lower risk of dementia, where the calculated odds ratio for all cause dementia in women was 0.23 (95%CI 0.09-0.61), suggesting a potential reduction in risk of developing dementia by 77%.

http://jama.jamanetwork.com/article.aspx?articleid=196197

These data provide insight into the potential for moderate alcohol consumption to reduce risk of cardiovascular disease, stroke, and dementia, but we must remind ourselves that these studies were focused on older adults, and perhaps earlier alcohol consumption has a different effect. Overall, these data are challenging to put together in a cohesive story, it may very well be that alcohol consumption in women between menarche and first pregnancy alters hormonal function in a manner that confers an increased risk of developing breast cancer, a risk that could generally be looked at as an increase in 10% risk for every drink one has on average per day, but there is also strong evidence that this same type of moderate alcohol consumption reduces risk of other diseases, and the question would still remain of what is the overall risk of mortality, and what should the alcohol consumption rate be recommended for younger women? Currently, the American Stroke Association guideline is that men have 1-2 glass of wine per day, while women should have 1 glass of wine per day (they typically recommend red wine, due to the potential benefits of antioxidants and polyphenols, but the epidemiological data rarely finds any difference in beneficial effects when the type of alcohol is controlled for), but should these guidelines be modified for younger women before their first pregnancy?

In a recent study published in the Journal of Clinical Oncology, alcohol consumption before and after breast cancer survival found that moderate alcohol consumption resulted in slightly better overall survival than non-drinkers, potentially suggesting that the benefits of moderate alcohol consumption slightly outweigh the negative effects of increased risk of breast cancer.

http://jco.ascopubs.org/content/early/2013/04/08/JCO.2012.46.5765.abstract

Overall, this is an extremely challenging issue that I believe has strong implications for public health, do any of you have suggestions on this?

Would you recommend a young woman to avoid alcohol completely? Should we take into account those with genetic predisposition to developing breast cancer?

Chad