Ellen Mahoney, MD PDF Print E-mail
October is Breast Cancer Awareness Month

Ellen Mahoney, MD trained as a surgeon at Stanford University School of Medicine after graduating with her MD degree from there in 1981. By 1986 she had risen to become Chief Resident in Surgery at Stanford, before going on to become a board–certified Fellow of the American College of Surgeons in 1993. In 2000 she moved to Arcata and opened her own practice in breast cancer surgery. She speaks frequently on breast cancer to community groups and serves as medical editor and expert contributor to the website of the Susan Love Foundation, a non–profit organization dedicated to the prevention of breast cancer through innovation, education, research and advocacy.

We asked Dr. Mahoney her opinions on wine consumption and Breast Cancer as a leader in her field, and here are her answers.

Wine is good for you!

The most important risk factors for breast cancer—being female and getting older—are not modifiable. Our literature is replete with papers searching for risk factors that are more under our control. These “modifiable” risk factors are generally weak and uncertain, and largely based on observed associations or self-reported data. These associations primarily serve as clues from the epidemiologists to the basic researchers, i.e. as challenges for the basic researchers to explore and explain. Unfortunately, when they get into the popular press, they are interpreted as causation by the general public and by less sophisticated clinicians. Alcohol use and breast cancer is an observed association still waiting for a mechanism to explain whether and how this can be the case. And the more rigorous the statistical methods used, and therefore the better the data, the weaker this association seems to be.

Associations have to be interpreted creatively and carefully. People who get lots of headaches use more aspirin. Does aspirin use cause headaches? Does the lack of aspirin cause headaches? Can any differences between premenopausal women and postmenopausal women be separated from the effects of age in epidemiologic studies? The mechanism of any association between breast cancer and alcohol has never been explained, though a hormone-based mechanism has been proposed, even though the link between hormones and breast cancer remains controversial. Excessive alcohol use can be linked to neglect of screening and health maintenance and to obesity. Is a slender and athletic drinker at equal risk of breast cancer as an obese alcoholic? Probably not.

One way of find risk factors for developing a disease is to look at the effect of that factor on patients who already have the disease. An Italian study published in the August 2008 issue of the Annals of Epidemiology (Dal Maso et al) showed that obesity, poor diet and smoking history were associated with risk of death in women diagnosed with breast cancer, but other factors such as hormone use, alcohol use, fat intake, and exercise were not risk factors. Another study (Reding et al)published recently also showed that women who regularly consumed a glass of alcohol (3-7 drinks a week) in the 5 years prior to a diagnosis of breast cancer had improved survival. A third recent study, published in the Journal of Clinical Oncology in July 2008 found that regular alcohol use was associated with improved prognosis in breast cancer patients.

But even if regular wine drinking does not worsen the prognosis of breast cancer survivors, it is still theoretically possible that alcohol could be associated with a greater incidence of the disease, and there are older studies which indicate this might be the case. There are problems with methodology with these older studies, though. In most, alcohol use depended entirely on the patients’ memory of their intake in the past and self-reporting on a questionnaire (Viel, Willett, Deandrea, Longnecker). In at least one case, re-analysis of the raw data has led to a reversal of the association (Zhang).

Another hint that this association is weak or indirect in the studies that show a positive relationship between the risk of breast cancer and low to moderate alcohol consumption is the inconsistency in the details of the supposedly significant influence. Some studies say that it is the lifetime consumption that is most important, not recent consumption, and others say the opposite. Results for the age of the patient, type of alcohol used or menopausal status are contradictory from study to study. If the effect of alcohol on breast cancer risk were important, it would likely be consistent, and it isn’t.

Bessaoud and Daures, reporting in the June 2008 issue of Annals of Epidemiology, looked at 437 newly-diagnosed French breast cancer patients matched with 922 residence- and age-matched controls. They found that women who consumed 1.5 drinks a day, or less, had a significantly lower risk of breast cancer than non-drinkers. Specifically, women who consumed a glass of wine a day had about 50% less breast cancer than non-wine drinkers. With more than 2 glasses of wine a day, the rate of breast cancer went up, but did not reach significance. This is a recent paper with fairly good methodology, and it is very reassuring to the wine lover.

There are other papers which show a clear association between heavy drinking and breast cancer, but as the alcohol consumption rises the confounding factors and complexity also increase, including the ability of the liver to clear other substances from the bloodstream. No one would ever argue that heavy drinking of any alcoholic beverage is beneficial. Light to moderate use seems to be associated with either lower risk of breast cancer, or a very slightly increased risk which is not statistically significant.

Basic scientists, trying to figure out the possible associations, have looked at resveratrol, a chemical found naturally in red wine, and found that it may have anticancer effects. This work is early, however, and wine is a complex liquid with many components.

Most women who get breast cancer in the US these days are treated and live out a normal life span, only to die of cardiovascular disease like most American women. There are some compelling associations showing that alcohol use, especially wine, is associated with a lower risk of cardiovascular disease and death. The same 1-2 glasses of wine a day that may lower breast cancer risk also lowers the risk of death from cardiovascular disease, and the evidence for that relationship being causal is stronger than the evidence that wine drinking raises risk.

The net finding of all of this effort is that the better the data, the better the evidence that a glass or two of wine a day is actually good for you. And a happy attitude resulting from a life well-enjoyed is especially good for you. If you decide that a glass of wine taken regularly fits into your life plan, make sure that it is the best wine you can obtain, then sit back and enjoy it thoroughly, hopefully in the company of good friends.

Bon appetit!

 

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