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

To compare the separate and combined effects of alcohol drinking and smokin g between the 2 sites, we evaluated 274 men with oral cancer, 364 with phar yngeal cancer and 1,254 controls, frequency-matched for age and area of res idence, from Italy and Switzerland. Extremely elevated risk increases for o ral cancer (odds ratio, OR = 228) and pharyngeal cancer (OR = 100) were fou nd for the highest joint level of drinking (greater than or equal to 77 dri nks/week) and smoking (greater than or equal to 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 c ancer was about 2-fold greater than that for pharyngeal cancer at each comb ined level of smoking and drinking, except at low levels of drinking in smo kers. A clear departure from risk difference additivity was present for bot h oral and pharyngeal cancer in individuals heavily exposed to both factors versus non-smoking abstainers/light drinkers. Our findings thus help expla in observations from descriptive epidemiology that, if smoking level in a p opulation does not change substantially, but alcohol consumption increases, increase in oral cancer would be greater than at any other site in the upp er aero-digestive tract, including cancer of the pharynx. (C) 1999 Wiley-Li ss, Inc.