Does Alcohol Cause Cancer?August 2, 2016 | Author: Susan Silberstein PhD
Wine-lovers often revel in the knowledge that resveratrol compounds in red wine confer anti-cancer protection. However, it’s not the alcohol that is beneficial. You can get plenty of resveratrol in grapes and berries, without including the alcohol. And that is hugely important. Most people know that drinking alcohol comes with health risks, but it appears that alcohol is more dangerous than we previously thought. After more than 10 years of research, scientists have concluded definitively that alcohol causes cancer.
Alcohol is the common term for ethanol or ethyl alcohol, a chemical substance found in beer, wine, and liquor (as well as in some medicines, mouthwashes, household products, and plant essential oils). Alcoholic beverages vary greatly in the amount of alcohol content:
- Beer typically contains up to 7% alcohol
- Wines contain 10-20% alcohol
- Hard liquor such as whiskey, gin, vodka or rum typically contains at least 35-40% alcohol
According to the National Institute on Alcohol Abuse and Alcoholism, a standard alcoholic drink in the United States contains 14 grams of pure alcohol, generally the amount found in:
- 12 ounces of beer
- 5 ounces of wine
- 5 ounces (a “shot”) of 80-proof liquor
Research evidence indicates that the more alcohol a person drinks—particularly regularly over time—the higher his or her risk of developing an alcohol-associated cancer.
Evidence Linking Alcohol to Cancer
According to a new literature review published online on July 21 in Addiction and on July 27 in Medscape Medical News, there is strong epidemiological evidence that alcohol causes at least seven different types of cancer.
Study author Jennie Connor, MPH, of the Department of Preventive and Social Medicine at the University of Otago in New Zealand, confirmed that drinking alcohol can cause cancer of the pharynx, larynx, esophagus, liver, colon, rectum and breast.
The International Agency for Research on Cancer (IARC) has long identified alcohol consumption as being causally associated with these cancers. Based on data from 2009, an estimated 3.5 percent of all cancer deaths in the United States (about 19,500 deaths) were alcohol related. In 2012, alcohol was estimated to have caused approximately half a million cancer deaths (nearly six percent) worldwide. The 2014 Report on Carcinogens issued by the National Toxicology Program of the US Department of Health and Human Services lists consumption of alcoholic beverages as a known human carcinogen. In 2015, scientists at the Harvard University School of Public Health and Brigham and Women’s Hospital reported in the British Medical Journal on a 30-year review of nearly 136,000 individuals. Overall, those who drank more showed a higher risk of cancer. Among women, even one drink a day contributed to a 13% higher risk of developing alcohol-related cancers, primarily breast cancer. For men, up to two drinks a day also increased the risk of certain cancers. The risk is even higher for men who smoke, or had smoked and quit, than for non-smokers.
Types of Cancer Caused by Alcoholic Beverages
Clear patterns have emerged between alcohol consumption and the development of specific types of cancer:
- Head and Neck Cancers: Alcohol consumption is a major risk factor for certain head and neck cancers, particularly cancers of the mouth, throat, and larynx. People who consume 50 or more grams of alcohol per day (3.5+ drinks daily) have two to three times greater risk of developing these cancers than nondrinkers.
- Esophageal Cancer: Alcohol consumption is also a major risk factor for squamous cell carcinoma of the esophagus. Some researchers found that drinking 2.5 beers or three glasses of wine a day increases your chances of getting cancer of the pharynx, larynx or esophagus by four to seven percent as compared with those who drink no alcohol at all. Furthermore, people who use both alcohol and tobacco have a much greater chance of developing cancers of mouth, throat, larynx, and esophagus than people who use either alcohol or tobacco alone.
- Liver cancer: Alcohol consumption is a primary cause, not only of cirrhosis of the liver, but also of liver cancer (along with the hepatitis B and C viruses).
- Breast cancer: More than 100 epidemiologic studies have consistently found an increased risk of breast cancer associated with increased alcohol intake. A meta-analysis of 53 of these studies on a total of 58,000 women with breast cancer showed that women who drank three alcoholic beverages a day had 1.5 times the risk of developing breast cancer as nondrinkers. For every 10 grams of alcohol consumed per day (slightly less than one drink), many researchers observed a seven percent increase in the risk of breast cancer. According to the Million Women Study conducted in the United Kingdom of more than 28,000 women with breast cancer, every 10 grams of alcohol consumed per day was associated with a 12 percent increase in risk.
- Colorectal cancer: Alcohol consumption is also associated with an increased risk of cancers of the colon and rectum. A meta-analysis of 57 studies on alcohol consumption and colorectal cancer risk showed that people who regularly drank 50 or more grams of alcohol per day (approximately 3.5 drinks) had a 150% greater risk of developing colorectal cancer than nondrinkers or occasional drinkers.
How Does Alcohol Increase the Risk of Cancer?
Scientists have identified multiple ways that alcohol may increase the risk of cancer, including the following mechanisms:
- When ethanol in alcoholic drinks breaks down, it forms acetaldehyde, a toxic chemical and probable human carcinogen which can damage cellular DNA and protein.
- Alcohol produces reactive oxygen species (oxygen-containing molecules or free radicals), which damage DNA, proteins, and fats through a process called oxidation.
- Alcohol impairs the body’s ability to break down and absorb a variety of cancer-protective nutrients like vitamins A, C, D and E, folates, and carotenoids.
- Alcohol increases blood levels of estradiol, a hormone linked to breast cancer.
- Alcoholic beverages may also contain a variety of carcinogenic contaminants that are introduced during production, including nitrosamines, hydrocarbons, and asbestos.
- In smokers, alcohol creates a pathway which allows carcinogens to penetrate the mucous membranes of the respiratory and upper digestive tract.
Is it Too Late if You’re Already a Drinker?
What happens to cancer risk after a person stops drinking alcohol? If you quit drinking or cut back on alcohol intake, you definitely have a chance to lower your cancer risk, but it may take many years before your risk drops down to that of a non-drinker.
A pooled analysis of 13 studies of persons with cancer of the mouth and throat found that alcohol-associated cancer risk did not begin to decrease until at least 10 years after stopping alcohol drinking. A review of five studies of ex-drinkers found that the risk of esophageal cancer did not approach that of never-drinkers for at least 15 years.
Bottom Line: If you don’t drink, don’t start. If you do drink, stop now or at least cut down. Even drinking half your normal portion or half as often could cut your cancer risk by 50%. And if you’re a smoker, stop now!
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 Cao Y, Willett W, Rimm EB et al. Light to moderate intake of alcohol, drinking patterns, and risk of cancer: Results from two prospective US cohort studies. August 18, 2015. BMJ 2015;351:h4238. http://www.bmj.com/content/351/bmj.h4238
 Mulcahy N. No Confusion: Alcohol Causes Seven Cancers. Medscape Medical News July 27, 2016.
 NTP (National Toxicology Program). 2014. Report on Carcinogens, Thirteenth Edition. Research Triangle Park, NC: U.S. Department of Health and Human Services, Public Health Service. http://ntp.niehs.nih.gov/pubhealth/roc/roc13/