How can drinking too much alcohol cause cancer?

Dr. Michael Roizen, MD
Internal Medicine
There are two theories why excessive drinking causes cancer. The first and most widely held explanation is that use of alcohol induces or increases the production of an enzyme that breaks down alcohol. This enzyme breaks down not only alcohol but also other foreign substances, often creating carcinogenic compounds in the process. That is why smokers in particular need to avoid drinking alcohol. The combination is deadly. The same enzyme that breaks down alcohol and hence increases when you are drinking, also breaks down the nitrosamines in cigarette smoke into a carcinogenic form. By stimulating the production of this enzyme, alcohol increases the risk of cancer from smoking. The RealAge (physiologic age) effect can make someone as much as five to ten years older.

That's why Senator Joe Bruno did the citizens of New York State such a huge favor by having cigarettes banned from bars. By not allowing a mixture of smoke and alcohol, the extra toxicity and carcinogenic elements you would get by drinking alcohol and inhaling cigarette smoke were and will be diminished.

A second explanation for the higher incidence of cancer among heavy drinkers is that alcohol itself contains low levels of cancer-causing substances. The risk of throat and digestive track cancers increases two to ten times among heavy drinkers, depending on the kind of cancer. Women in particular have to be careful: Women who drink too much are at twice the risk of uterine, cervical cancers, and probably breast cancers, although the data are not definitive enough to assert a direct cause and effect.
Elizabeth Boham, MD, MS, RD
Nutrition & Dietetics
There has been a lot of research connecting alcohol intake and breast cancer. In fact, much of the research shows a linear relationship between a women's intake of alcohol and her risk of getting breast cancer. This means that as a women's alcohol intake increases, so does her breast cancer risk. The reasons for this are multifactoral. First, alcohol needs to get metabolised by the liver. Too much alcohol may weaken the liver's ability to detoxify other toxins that a person is exposed to. Secondly, alcohol uses up b vitamins during its metabolism. B vitamins are necessary for fixing broken DNA. So if someone drinks too much alcohol, they may become deficient in b vitamins and increase their risk of cancer. Thirdly, a diet high in alcohol may be associated with other unhealthy lifestyle choices that may also increase a women's risk of getting breast cancer. So what is too much? Stick to 5 or fewer drinks per week and usually one or fewer drinks per day. Remember one drink is equal to 5 oz of wine, one beer or 1.5 oz of hard alcohol.  

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.