Here is an essay on ‘Alcohol and Cancer’ which states – How alcohol acts synergistically with tobacco to increase cancer risk.
The use of alcohol is associated with an increased risk of developing several types of cancer, especially in tissues where alcohol makes direct contact with an epithelium. The most common problems are cancers of the mouth, throat, larynx, esophagus, and stomach.
Excessive drinking is also the main cause of cirrhosis, a degenerative disease in which liver cells are destroyed and replaced by scar tissue and fat. In addition to experiencing poor liver function, individuals with cirrhosis are at increased risk for developing liver cancer.
A striking feature of the cancer risk created by alcohol involves its interaction with tobacco, a phenomenon illustrated in Figure 10 for cancer of the mouth and throat (oropharyngeal cancer). Cancer of the mouth and throat is rare in people who do not drink alcohol or smoke, but its rate increases about 6-fold in people who are regular drinkers (but not smokers) and 7-fold in people who are regular smokers (but not drinkers).
You might therefore expect that for people who drink and smoke, the increase in risk would be no more than 13-fold (i.e., the alcohol- related risk added to the smoking-related risk). In reality, people who are both drinkers and smokers exhibit a 38- fold increase in cancer incidence.
This means that the interaction between alcohol and tobacco is synergistic; that is, the two agents act together in a cooperative way to produce an effect that is greater than the sum of the effects produced by each acting alone.
The existence of synergism between alcohol and tobacco can be explained by the fact that the two substances trigger different events in the pathway leading to cancer. We have already seen that tobacco smoke contains dozens of chemicals that are potent carcinogens and mutagens. Alcohol, on the other hand, is only a weak carcinogen when tested in animals and does not seem to cause mutations. Repeated exposure to alcohol, however, causes tissue damage and cell death in regions of the body that are in direct contact with the alcohol.
In response to such damage, the surviving cells grow and divide to replace the cells that have been destroyed. It is this ability to trigger cell proliferation (rather than mutation) that appears to explain the role played by alcohol in the development of cancer. Alcohol and tobacco are therefore a deadly combination because tobacco smoke contains potent carcinogens that create DNA mutations and alcohol then stimulates the proliferation of the genetically damaged cells.
