Indeed, it is estimated that 75 percent of all oral and pharyngeal cancers in the United States are due to drinking and smoking. But, even among nonsmokers, risks of oral and pharyngeal cancers rise with increasing intake of alcohol. While heavy consumption of all types of alcoholic beverages seems to increase risk of these cancers, there is some suggestion that the association is more pronounced for hard liquor and beer than for wine. In some areas of the world, particular alcoholic beverages have been associated with exceptionally high rates of esophageal cancer. The variation in risk by type of beverage, however, suggests that substances other than the alcohol may in some instances contribute to the risk.
Alcohol is also a recognized cause of liver cancer.
By altering liver function and the liver's ability to metabolize some substances into compounds that may be carcinogenic or to deactivate certain existing carcinogens, alcohol's effects on the liver may influence not only liver cancer but cancers at other sites as well. Further research is needed to clarify whether the association between alcohol and breast cancer is causal in nature. Several epidemiologic studies suggest that alcohol may induce colorectal cancers, particularly rectal cancer, but the findings are not totally consistent. Moderation of intake is the key to prevention of alcohol-induced cancer. Because many of the cancers induced by alcohol result from heavy consumption, reducing levels of consumption will considerably lessen the risk.