Comparison of the effect of smoking and alcohol drinking between oral and pharyngeal cancer

Abstract

To compare the separate and combined effects of alcohol drinking and smoking between the 2 sites, we evaluated 274 men with oral cancer, 364 with pharyngeal cancer and 1,254 controls, frequency‐matched for age and area of residence, from Italy and Switzerland. Extremely elevated risk increases for oral cancer (odds ratio, OR = 228) and pharyngeal cancer (OR = 100) were found for the highest joint level of drinking (≥77 drinks/week) and smoking (≥25 cigarettes/day). Ratios of ORs between oral cancer and pharyngeal cancer vs. controls, obtained by polytomous logistic regression, suggested that the risk increase for oral cancer was about 2‐fold greater than that for pharyngeal cancer at each combined level of smoking and drinking, except at low levels of drinking in smokers. A clear departure from risk difference additivity was present for both oral and pharyngeal cancer in individuals heavily exposed to both factors versus non‐smoking abstainers/light drinkers. Our findings thus help explain observations from descriptive epidemiology that, if smoking level in a population does not change substantially, but alcohol consumption increases, increase in oral cancer would be greater than at any other site in the upper aero‐digestive tract, including cancer of the pharynx. Int. J. Cancer 83: 1–4, 1999.