The role of alcohol in oesophageal cancer in non-smokers, and of tobacco in non-drinkers.

Data from a hospital-based case-control study of oesophageal cancer conducted in Northern Italy were used to analyse the risk associated with alcohol in non-smokers and with tobacco in non-drinkers. Out of a total of 250 cases (198 males, 52 females) and 1,089 controls (800 males, 289 females), there were 38 cases and 404 controls who described themselves as lifelong non-smokers. Among these persons, the relative risk was not different for teetotallers and moderate drinkers (less than 4 drinks per day), but increased markedly for higher levels of alcohol consumption. The point estimates were 2.1 for 4 to 8 and 3.6 for over 8 drinks per day, and the trend in risk was statistically significant. Likewise, among 30 cases and 189 controls who were non-drinkers, the point estimates were 2.0, 3.9 and 6.2 for smokers of less than 15, 15-24 and greater than or equal to 25 cigarettes per day, with, again, a statistically significant trend. This study supplies further evidence that both alcohol and tobacco are strongly related to the risk of oesophageal cancer, even in the absence of exposure to the other risk factor. This confirms previous indications from a study in Calvados, France and also provides statistically significant epidemiological evidence of an independent role of exposure to tobacco alone in the aetiology of oesophageal cancer. The relative risks associated with exposure to either of the 2 factors among subjects not exposed to the other were readily comparable to the estimates adjusted for the other factor in the overall data-set, thus further confirming the independent effect of alcohol and tobacco on oesophageal carcinogenesis.