Tobacco, alcohol, asbestos, and nickel in the etiology of cancer of the larynx: a case-control study.

A case-control study of laryngeal cancer was conducted in southern Ontario between 1977 and 1979 with 204 subjects with newly diagnosed cancer and 204 controls, individually matched by sex, age, and residence. Tobacco products and alcohol showed strong associations with cancer of the larynx for males, with relative risks (RR) for users of cigarettes, cigars or cigarillos, pipes, and alcohol of 6.1, 2.9, 1.6, and 5.2, respectively. The population attributable risk percent for males using tobacco products and alcohol together was estimated to be 94%. Cigarette smoking was also an important risk factor for females, although the small number of female pairs (20) precluded any meaningful detailed analysis of other possible risk factors. The RR for males for exposure to asbestos after the effects of cigarette smoking were controlled was 2.3, and the effects seemed restricted to cigarette smokers. The findings on asbestos were based on small numbers of cases and controls exposed and consequently were subject to large sampling errors. The estimate was consistent, however, with that from other studies and supported a causal role for asbestos exposure and cancer of the larynx. The RR for males for exposure to nickel was 0.9.