Cancer and non-cancer controls in studies on the effect of tobacco and alcohol consumption.

A comparison of risk estimates using controls with other cancers versus controls with acute diseases unrelated to tobacco and alcohol consumption in the study of the effect of these two factors has been performed using data on tumours of the oral cavity and pharynx from an ongoing case-control surveillance programme in Northeastern Italy. Similar results were obtained using either type of controls: as compared to never smokers, moderate smokers (less than or equal to 14 cigarettes/day) showed age- and sex-adjusted odds ratio (OR) = 5.2 (95% confidence interval (CI): 2.9-9.2) when using cancer controls and 5.8 (95% CI: 3.3-10.1) when using non-cancer controls. Similarly, those who had smoked for 40 years or longer showed ORs of 7.4 (95% CI: 4.0-13.6) and 8.8 (95% CI: 4.9-15.6), respectively, using cancer and non-cancer controls. For moderate drinkers of alcoholic beverages (21-34 drinks/week) and heavy drinkers (greater than or equal to 84 drinks/week) the ORs, as compared to individuals who drank less than 21 drinks/week, were 1.9 (95% CI: 1.0-3.6) and 2.2 (95% CI: 1.2-4.0) and 10.6 (95% CI: 5.5-20.6) and 11.4 (95% CI: 6.0-21.4) using cancer and non-cancer controls, respectively. The same comparability of ORs for tobacco- and alcohol-related variables using either type of controls was observed when separate analyses of the two sexes were performed. The close similarity between cancer and non-cancer controls in studies on tobacco- and alcohol-related risks may be exploited when the choice of other types of controls would increase the costs and the feasibility of the study, and thus hamper its statistical power.(ABSTRACT TRUNCATED AT 250 WORDS)