It has long been known that drinking alcohol can increase a woman’s risk of breast cancer. A recent review from the French International Agency for Research in Cancer looked at 15 meta-analyses on the risk relationship between alcohol consumption (including light consumption) and the risk of breast cancer. (A meta-analysis is a statistical approach to combine the results from multiple studies in an effort to improve estimates of the size of an effect and/or to resolve uncertainty when reports disagree.) All but two of these analyses showed a dose-response relationship between alcohol consumption and the risk of breast cancer, even at low levels of consumption.
Researchers at the University of Houston have found a cancer-causing gene that is triggered by alcohol. Cancer biologist Chin-Yo Lin says: "Our research shows alcohol enhances the actions of estrogen in driving the growth of breast cancer cells and diminishes the effects of the cancer drug Tamoxifen on blocking estrogen by increasing the levels of a cancer-causing gene called BRAF." Along with colleagues, he published his findings in PLOS ONE, an open access, peer-reviewed scientific journal published by the Public Library of Science. The authors estimate that tens of thousands of breast cancer cases in the U.S. and Europe each year are attributable to alcohol consumption and that drinking is also associated with an increased risk of disease recurrence in women with early stage breast cancer. Another key finding was that alcohol weakened Tamoxifen's ability to suppress the rapid growth of cancer cells. Lin and his colleagues posit that their results suggest exposure to alcohol may affect a number of cancer-related pathways and mechanisms. He says their findings have implications for women who are undergoing hormone replacement therapy for menopausal symptoms, as alcohol can affect the actions of the hormones they take to manage their symptoms. The research highlights potential long-term health effects for college-age women, who might find themselves in situations where heavy or binge drinking is part of the social environment.
"We hope these and future findings will provide information and motivation to promote healthy behavioral choices, as well as potential targets for chemoprevention strategies to ultimately decrease breast cancer incidents and deaths within the next decade," Lin said. "We want to provide women, in general, with more information and insight to be better able to balance their consumption of alcoholic beverages with the potential health risks, including cancer patients who may want to take into consideration the potential detrimental effects alcohol consumption might have on treatments and modify their behavior and habits accordingly."
Alcohol may affect the growth of cancers beyond the breast. A recent study from the University of Otago in New Zealand was published in the journal Addiction; it was also based on meta-analyses concerning alcohol and a variety of cancers. The author wrote ”even without complete knowledge of biological mechanisms, the epidemiological evidence can support the judgement that alcohol causes cancer of the oropharynx, larynx, oesophagus, liver, colon, rectum and breast. The measured associations exhibit gradients of effect that are biologically plausible, and there is some evidence of reversibility of risk in laryngeal, pharyngeal and liver cancers when consumption ceases. The limitations of cohort studies mean that the true effects may be somewhat weaker or stronger than estimated currently, but are unlikely to be qualitatively different.”
How can we wisely react to these recent findings? Alcohol has been a part of the human experience since our early beginnings. Many other factors are closely related to the development of cancer, such as ionizing radiation, tobacco, the papilloma virus, UV exposure, family genetics, environmental toxins, unhealthy diets et al. Cancer incidence rises with age, along with DNA changes in our genome. Alcohol is clearly not the only risk factor for cancer, but it is one we can control. I think it is wise for women to be very careful about alcohol use, not to exceed one drink a day, and preferably use less, such as a drink only on special occasions. Women dealing with breast cancer should stop altogether. Men who drink daily should limit their intake to one or two drinks at most. If there is a strong family history of colon cancer or other cancers, stop completely. If you are diagnosed with cancer, stop completely. Go to AA meetings. If you don’t believe in a God, try nature or your sober friends for support. My partner used to say ”I need an attitude adjustment” before having a glass of wine. Now he says “Let’s meditate”.
Sadja Greenwood, MD, MPH