The effects of smoking and alcohol use on risk of upper aero-digestive cancers
Upper aero-digestive tract cancers (UADT), especially those of the oral cavity, pharynx, and larynx, are often referred to as alcohol-related cancers as it has been shown repeatedly that heavy drinkers, in particular, are at increased risk. The combination of heavy alcohol use and cigarette smoking is the key factor in increasing the risk of these cancers.
A distinguished group of scientists from the International Agency for Research on Cancer (IRAC).evaluated the role of alcohol and tobacco consumption, based on 2,252 upper aerodigestive squamous-cell carcinoma cases and 1,707 controls from seven centres in Brazil, Argentina, and Cuba. While this paper only supports much previous research, it is from a part of the world from which little information on the topic is available and it focuses on groups of people where the occurrence of such cancers is high.
The case-control analysis showed that both alcohol consumption and smoking tended to increase the risk of such cancers. However, the predominant cause of these cancers was the combination of smoking and alcohol consumption, with much higher risk than either exposure alone. The effects on risk were greater for smoking than for alcohol: for non-smokers, there was little effect of alcohol alone on risk. For non-drinkers, the risk of cancer associated with smoking was still increased, but was lower than it was for current drinkers.
Interaction of drinking and smoking: Overall, this study confirms that there is a tendency for an increase in risk for these cancers for both alcohol consumption and for tobacco use. More striking, however, was the strong interaction between these two exposures: heavy smokers and heavy drinkers were by far at the highest risk. For never-smokers, there was little effect of alcohol on the risk of these cancers, and none of the associations between alcohol and cancer among such subjects was statistically significant. As for the type of alcoholic beverage consumed, the risk for cancer was always highest among subjects stating that they consumed only aperitifs or spirits, with little apparent effect of the consumption of beer or wine.
An especially important finding in this study was that, among ex-drinkers and former smokers, the increased risks associated with alcohol and tobacco use decreased steadily as the time since quitting increased. As stated by the authors, most of these cancers "could be prevented by quitting the use of either of these two agents."