What are cancer-causing substances? If this question were put before educated elite community, including doctors, their response would invariably include: tobacco, pesticides and chemicals. Not even one in thousand would include alcoholic beverages. But the truth is often different from perception. Truth is objective. Perception is not. Truth is verified and verifiable. The truth about alcohol, unknown to many, is that alcohol is listed as a “proven human carcinogen”, by International Agency for Research on Cancer (IARC), a research body under World Health Organisation (WHO).  A carcinogen means “any substance or agent that tends to produce a cancer”. The IARC maintains four different groups of carcinogens.  Of this the first, i.e. Group-1, includes those substances that have been conclusively shown to cause cancers in humans. Alcoholic beverages are listed under Group-1 along with such other well-known carcinogens as tobacco, X-ray, benzene, formaldehyde etc.

 IARC’s rulings are the ultimate standard in terms of determining if something causes cancer and Group-1 is their highest risk category. It means that there is conclusive evidence that alcohol causes cancers in humans. In fact, the IARC has classified alcohol as a Group-1 carcinogen since 1988.  More recent reviews by other reputed agencies in the field of cancer research have also concluded that drinking alcohol indeed causes cancer.

In its press release No. 196 dated 2 November 2005, the IARC said: “Nearly 2 billion adults worldwide are estimated to consume alcoholic beverages regularly with an average daily consumption of 13gm of ethanol (about one drink). Alcohol consumption has already been shown to cause cancers of oral cavity, pharynx, larynx, esophagus, colorectal, liver, female breasts”.

Daniel E. Nelson et al of National Cancer Institute, USA found that alcohol consumption resulted in an estimated 18,200 to 21,300 cancer deaths. The majority of alcohol-attributable female cancer deaths were from breast cancer (56% to 66%), whereas upper airway and esophageal cancer deaths were more common among men (53% to 71%). Alcohol-attributable cancers resulted in 17.0 to 19.1 years of potential life lost for each death. Daily consumption of up to 20 grams of alcohol accounted for 26% to 35% of alcohol-attributable cancer deaths.

Cancers accounted for 22% of alcohol attributable deaths globally.

Citing the IARC, the World Health Organization in its Global Status Report on Alcohol and Health 2014 observed “alcohol consumption has been identified as carcinogenic for the following cancer categories: cancer of the mouth, nasopharynx, other pharynx and oropharynx, laryngeal cancer, oesophageal cancer, colon and rectum cancer, liver cancer and female breast cancer. In addition, alcohol consumption is likely to cause pancreatic cancer. The higher the consumption, the greater the risk for these cancers, with consumption as low as one drink per day causing significantly increased risk for some cancers, such as female breast cancer

According to WHO, globally, 50.1% of total alcohol is consumed in the form of spirits (whisky, brandy, rum, vodka etc). The second most consumed alcoholic beverage type is beer, which accounts for 34.8% followed by wine 8%. 

 Research has shown that all types of alcoholic drinks, including wine, beer and spirits, can increase the risk of cancer. The risk is linked to the actual alcohol (ethanol) in the drink, and increases with the amount drunk.  Ethanol is the most important carcinogen in all-alcoholic beverages.

Europe has the highest per-capita consumption of alcohol, reveals a 2014 report by the WHO. Europe has all the top ten alcohol consuming countries in the world, with Belarus at the top.

Research has shown that all types of alcoholic drinks, including wine, beer and spirits, can increase the risk of cancer. The risk is linked to the actual alcohol (ethanol) in the drink, and increases with the volume drunk. Ethanol is the most important carcinogen in all-alcoholic beverages.

Cancer Research, UK says that as little as three units (30ml) of alcohol a day can increase the risk of mouth, throat, food pipe, breast and bowel cancers. Alcohol causes about 12,500 of cancer cases every year in the UK. Cancer Research, UK further states that regularly drinking even small amounts of alcohol can increase the risk of breast cancer. A review of the evidence in 2012 concluded that having 1.5 drinks a day (i.e. 15ml of pure alcohol) could increase the risk of breast cancer by 5%. And the risk increases the more a woman drinks, several studies have found that each additional 10g of alcohol drunk a day increases the risk of breast cancer by about 7-12%.

Cancer Council, Australia categorically states that alcohol use is a cause of cancer and any level of alcohol consumption increases the risk of developing an alcohol related cancer.

“Alcohol is a carcinogen and should be treated as such,” was the message at the European Week Against Cancer held in Dublin in
May 2013.

At the moment, we are not entirely sure how alcohol acts to cause different types of cancer but there are several theories with good evidence. It is likely that alcohol causes different types of cancer in different ways, says Cancer Research, UK.

The theory with the strongest evidence is related to how our bodies process alcohol. It is converted into another chemical called acetaldehyde. Acetaldehyde can cause cancer by damaging our DNA and preventing it from being repaired. The IARC lists acetaldehyde associated with drinking alcohol as a Group-1 substance, which means it can cause cancer in humans. Drinking alcohol greatly increases the level of acetaldehyde found in saliva. And a small initial study in 2012 found higher levels of DNA damage in the mouth cells of people after drinking alcohol.

Alcohol can also increase the level of hormones such as oestrogen in the body. Unusually high levels of oestrogen could cause
breast cancer.

Alcohol can even cause cirrhosis of the liver, by repeatedly damaging the liver’s cells. This in turn can cause liver cancer.

Alcohol makes it easier for cancer-causing chemicals, such as those found in tobacco, to be absorbed in the mouth or throat.

Alcohol reduces the amount of folate (folic acid) in our blood. Folate is a B vitamin that our cells need to create new DNA correctly.

Alcohol can cause highly reactive molecules known as Reactive Oxygen Species or ROS, to be produced in our bodies and particularly in the liver. These molecules are damaging and they are usually kept at a low level, but when ROS levels are raised, they are known to
damage the DNA.

 Highlighting the urgent need to promote public awareness about alcohol being a human carcinogen, Daniel E. Nelson et al, in “Alcohol Attributable Cancer Deaths and Years of Potential Life Lost in United States”, published in April 2013 issue of American Journal of Public Health, concluded, “Stronger and more comprehensive individual and population level efforts are warranted to reduce cancer risk from alcohol use. Clear and consistent statements from medical and public health organisations and providers are needed emphasising that:

 (1) Alcohol is a known human carcinogen,

 (2) Cancer risk increases considerably at high consumption levels but there is no safe level at which there is no cancer risk, and

 (3) Alcohol use should be lowered or avoided to reduce cancer risk.”

The writer is advisor, policy affairs at Crop Care Federation of India