A comparison of the joint effects of alcohol and smoking on the risk of cancer across sites in the upper aerodigestive tract.

A unified analysis of the combined effects of alcohol and smoking in cancers of the upper aerodigestive tract was conducted using polychotomous logistic regression to determine if, at the same level of exposure, risk varies significantly across pathological sites. Data from a case-control study in northern Italy include males with tumors of the oral cavity/pharynx, larynx, and esophagus and males admitted to the hospital for acute illnesses not related to alcohol and smoking. The combined alcohol and smoking risks for oral cavity/pharynx cancer in these data were significantly greater than those for either laryngeal or esophageal cancer, but esophageal cancer and laryngeal cancer could not be distinguished based on risk. The differences may lie in the presence of unspecified factors in the oral cavity and pharynx, but not in the other upper aerodigestive tract sites, which potentiate the effects of alcohol and smoking in the oral cavity/pharynx.