Alcohol as a cause of cancer.

This is a review of the epidemiologic literature on alcohol and risks of various cancers. Alcohol has consistently been related to risks of squamous cell carcinomas of the mouth, oral pharynx, larynx, and esophagus in multiple studies of varying design. The joint effects of alcohol and smoking are greater than additive, and are probably multiplicative, suggesting biological synergism. All major types of alcoholic beverages have been casually implicated in the genesis of these diseases. The influence of alcohol on risks of upper aerodigestive tract cancers may be greater in persons with marginal nutritional status than in better-nourished individuals. Alcohol also has been associated with an increased risk of adenocarcinomas of the esophagus, gastro-esophageal junction, and gastric cardia, but the relationship is not as strong as for squamous cell esophageal carcinomas. Alcohol and tobacco account for over 80% of the squamous carcinomas of the mouth, pharynx, larynx, and esophagus in the United States. Risks of cancers of the distal stomach, pancreas, colon, and rectum have not been consistently related to alcohol, although possible relationships between beer drinking and rectal cancer and between heavy use of alcohol and pancreatic cancer warrant further study. Studies of alcohol and liver cancer, in which the confounding influence of hepatitis B was considered, have yielded inconsistent results and should be replicated. An association between heavy alcohol use and breast cancer has been observed in most studies, even after controlling for known risk factors for breast cancer, and additional investigations of this issue are warranted.