Risk factors for oral and pharyngeal cancer in never smokers

Information on the etiology of oral and pharyngeal cancer in never smokers should help us to understand and quantify risk factors for the disease in the absence of the residual confounding and interaction by smoking. Out of a total of 528 cases with histologically confirmed incident cancers of the oral cavity and pharynx, 42 (10 men and 32 women) who described themselves as lifelong non-smokers were considered. Controls were 864 lifelong non-smokers (442 men and 422 women) admitted to hospital for acute, non-neoplastic, non-alcohol-related conditions. The major risk factor for cancer of the oral cavity and pharynx in never smokers was alcohol consumption (mainly wine) with an odds ratio (OR) about three-fold higher in drinkers than non-drinkers. A direct relation was also found for the duration of the habit, with an OR of 3.6 (95% confidence intervals, CI, 1.2-11.2) for drinking for 35 years or longer. Among the few selected indicator foods considered, a direct association was found with butter (OR 2.7, 95% CI 1.4-5.1 for high intake compared to low), and a non-significant inverse association with carrots (OR 0.6, 95% CI 0.3-1.3) and fresh fruit (OR 0.7, 95% CI 0.3-1.6) for the highest tertile of intake compared to the lowest. Thus, even in the absence of smoking, reducing alcohol and saturated fat intake and increasing fruit and carrot consumption may have favorable effects on oral and pharyngeal cancer risk.