Attributable risk for laryngeal cancer in northern Italy

Using data from a case-control study conducted between 1986 and 1992 in Northern Italy on 367 cases of laryngeal cancers (350 men and 17 women) and 1931 hospital controls (1373 men and 558 women), we estimated the relative risks (RR) and the population attributable risks (AR) for laryngeal cancer in relation to tobacco and alcohol consumption and a diet containing little fresh fruit and vegetables (low beta-carotene intake). In men, the RR and their 95% confidence interval (CI), derived from multiple logistic regression, including terms for center, age, and education, plus, simultaneously, tobacco, alcohol, and beta-carotene) were 3.3 (95% CI, 1.9 to 5.5) for ex- or moderate smokers (< 15 cigarettes/day) and 8.8 (95% CI, 5.2 to 14.8) for heavy current smokers compared to never smokers; the RR were 1.5 (95% CI, 1.0 to 2.2) for drinkers of 6 to < 8 alcoholic drinks/day and 2.2 (95% CI, 1.6 to 3.0) for drinkers of 8 or more drinks/day compared to teetotallers or moderate drinkers; with respect to carotene intake the RR were 1.4 (95% CI, 1.0 to 2.0) for the intermediate tertile and 1.8 (95% CI, 1.3 to 2.5) for the lowest tertile, as compared to the highest tertile of intake. AR were estimated assuming a multiplicative model: the single factor with the largest AR was smoking, which accounted for about 77% of laryngeal cancers in men; alcohol intake explained about 25% of cases, low beta-carotene intake accounted for about 18% of cases, and together the three factors were responsible for about 86% of laryngeal cancers in men.