In 1988, the International Agency for Research on Cancer (IARC) declared that alcohol was a carcinogen.
The World Cancer Report released in 2014 highlighted the role of alcohol in cancer, finding that alcohol accounts for 3.5% of cancers (about 1 in 30 cancer deaths) globally.
Recent data indicate that the proportion of cancers attributable to alcohol worldwide has increased.
In 2012, alcohol consumption caused 5.5% of all cases of cancer and 5.8% of all cancer deaths. This increase is believed to be attributable primarily to an increase in the prevalence of drinkers and in the amount of alcohol consumed, particularly by women.
The fact that alcohol is a carcinogen has been clearly confirmed according to an article published in Medscape Oncology.
Jürgen Rehm, PhD, Director of the Social and Epidemiological Research Department at the Centre for Addiction and Mental Health in Toronto, Ontario, Canada, describes how our knowledge about the role of alcohol in cancer has advanced during the past year. "Very simply, the cancers that have been determined previously to be caused by alcohol have been confirmed. There is no discussion about whether alcohol causes these cancers. The fact that alcohol is a carcinogen has been clearly confirmed."
The cancers that Dr Rehm refers to include those of the oral cavity, pharynx, larynx, esophagus, breast, colon, rectum, gallbladder, and liver. It is also considered probable that alcohol increases the risk for pancreas cancer, although the evidence is inconclusive.
Recent evidence suggests that melanoma, as well as cancers of the stomach, lung, and prostate, may be associated with alcohol consumption, although only with high levels of consumption and to a moderate excess risk. There are also differences of opinion on whether liver cancer should be considered an alcohol-related cancer and whether the risk for colorectal cancer is increased in both sexes or only in men.
The increased risk for cancer appears to be significant at lower levels of alcohol consumption in women than in men.
Of note, this study also examined cancer risk associated with alcohol intake and smoking, including those who had never smoked ("never smokers"). The risk for cancer, including alcohol-related cancers, was not elevated in men who had never smoked. In women, however, even in never smokers, the risk for alcohol-related cancers was increased because of the association of alcohol with breast cancer.
Additional findings of noted that alcohol consumption was significantly related to breast cancer risk; each 10-g/day increase in alcohol intake raised the hazard ratio by 4.2%.
How Much Alcohol Raises Cancer Risk? A persistent question is: What constitutes safe consumption? Is there a definite, known level of alcohol consumption that is not associated with increased cancer risk? Unfortunately, given our current state of knowledge, this "safe zone"—if it exists—cannot be defined. Heavy alcohol consumption has been consistently linked with cancer, but less is known about the impact of light or moderate drinking on cancer risk.Many studies have defined light, moderate, and heavy alcohol intake differently.
Despite differences in standard drink size, all studies have made some attempt to classify drinkers according to typical daily consumption of alcohol. Definitions of "light-to-moderate" and "heavy" drinking are arbitrary as used in epidemiologic research. Typically, the ingestion of three (two for women) or more standard-sized drinks per day is termed "heavy" and fewer than three (two for women) standard-sized drinks daily is "light-to-moderate" drinking. And it has been consistently found that heavy drinking elevates the risk for certain cancers substantially.
Recent studies have not provided strong evidence of an association between alcoholic beverage type and cancer. Researchers found the same risk with all beverage types, concluding that ethanol, but not other components of alcoholic beverages, was the culprit.
The role of smoking. An interaction exists between alcohol consumption, tobacco, and cancer. In fact, evidence suggests that the combined effect of alcohol and smoking on the incidence of head and neck cancer (oral cavity, pharynx, and larynx) is greater than multiplicative. This interaction is biologically plausible. Alcohol can act as a solvent for carcinogens in cigarette smoke and render the mucosa more permeable to these carcinogens.
The bottom line - Alcohol is a modifiable risk factor for cancer. Of all dietary factors associated with cancer risk, alcohol has the strongest and most consistent evidence for a carcinogenic effect.