Alcohol and Cancer: A Statement of the American Society of Clinical Oncology
Nov 7, 2017
Evidence to Link Alcohol Consumption to Specific Cancers
The relationship between drinking alcohol and cancer risk has been evaluated extensively in epidemiologic case-control and cohort studies. In a thorough systematic review of the world’s evidence that adhered to prespecified criteria for drawing inferences, a World Cancer Research Fund/American Institute for Cancer Research (AICR) report judged the evidence to be convincing that drinking alcohol was a cause of cancers of the oral cavity, pharynx, larynx, esophagus, breast, and colorectum (in men). Also, alcohol was judged to be a probable cause of increased risk of liver cancer and colorectal cancer (in women). An updated review of the evidence for liver cancer upgraded the conclusion for an association between alcohol drinking and liver cancer to convincing. The International Agency for Research on Cancer (IARC), a branch of WHO, has assessed the evidence and come to virtually identical conclusions: that alcohol is a cause of cancers of the oral cavity, pharynx, larynx, esophagus, colorectum, liver (ie, hepatocellular carcinoma), and female breast. For esophageal cancer, the association with alcohol drinking is largely specific to squamous cell carcinoma. The more that a person drinks, and the longer the period of time, the greater their risk of development of cancer, especially head and neck cancers.
The Mechanistic Role of Alcohol in Carcinogenesis
When the evidence of alcohol’s role in carcinogenesis is considered, a key point is that, in biochemical reactions that are sequentially catalyzed by alcohol dehydrogenase and aldehyde dehydrogenase, ethanol is eliminated from the body by its oxidation first to acetaldehyde and then to acetate. Ethanol per se is not mutagenic, but acetaldehyde is carcinogenic and mutagenic, by binding to DNA and protein.
Impact of Smoking in Combination With Alcohol Consumption
Some malignancies are causally linked to both alcohol drinking and cigarette smoking; in some cases, an established synergistic interaction between alcohol drinking and cigarette smoking exists. This means that, in cancers for which both alcohol drinking and cigarette smoking are causal factors, the cancer risks in those who are both alcohol drinkers and cigarette smokers are much larger than the risks seen for those who only drink alcohol or only smoke cigarettes. Specific upper aerodigestive tract cancers provide the strongest examples of robust synergistic interactions between alcohol drinking and cigarette smoking. A pooled analysis of 17 case-control studies identified a potent interaction between alcohol drinking and cigarette smoking in cancers of the oral cavity, pharynx, and larynx, and a review identified evidence of robust interaction in 22 of 24 published studies on oral, pharyngeal, laryngeal, and esophageal cancers. Despite the clear presence of synergistic interaction, the biologic underpinnings of the interaction between alcohol drinking and cigarette smoking are not well understood.
A Statement of the American Society of Clinical Oncology
Alcohol drinking is an established risk factor for several malignancies, and it is a potentially modifiable risk factor for cancer. The Cancer Prevention Committee of the American Society of Clinical Oncology (ASCO) believes that a proactive stance by the Society to minimize excessive exposure to alcohol has important implications for cancer prevention. In addition, the role of alcohol drinking on outcomes in patients with cancer is in its formative stages, and ASCO can play a key role by generating a research agenda. Also, ASCO could provide needed leadership in the cancer community on this issue. In the issuance of this statement, ASCO joins a growing number of international organizations by establishing a platform to support effective public health strategies in this area. The goals of this statement are to:
- Promote public education about the risks between alcohol abuse and certain types of cancer;
- Support policy efforts to reduce the risk of cancer through evidence-based strategies that prevent excessive use of alcohol;
- Provide education to oncology providers about the influence of excessive alcohol use and cancer risks and treatment complications, including clarification of conflicting evidence; and
- Identify areas of needed research regarding the relationship between alcohol use and cancer risk and outcomes.