MATE, COFFEE, AND TEA CONSUMPTION AND RISK OF CANCERS OF THE UPPER AERODIGESTIVE TRACT IN SOUTHERN BRAZIL

Consumption of mate, a tea-like infusion of the herb Ilex paraguariens is, is common in South America. Drinkers have high risks of upper aero digestive tract cancers, but it is conceivable that: this high risk ma y be attributable to confounding by smoking, alcohol and other exposur es. To test this hypothesis, we analyzed the data from a case-control study of upper aerodigestive tract cancers conducted in Southern Brazi l. We marched noncancer controls (N = 756) to cases (N = 378) on the b asis of age, sex, and period of admission. We estimated the effect of mate consumption by conditional logistic regression with adjustment fo r smoking, alcohol, sociodemographics, and several dietary items, cons idered as confounders. The unadjusted relative risk (RR) for all upper aerodigestive tract cancers was 2.1 [95% confidence interval (CI) = 1 .6-2.7]. Some excess risk persisted after adjustment for potential con founders (RR = 1.6; 95% CI = 1.2-2.2). Most of the excess risk for mat e drinkers was for oral (RR = 1.9; 95% CI = 1.1-3.3) and laryngeal (RR = 2.2; 95% CI = 1.1-4.5) cancers. There was no evidence of associatio ns with coffee and tea drinking. We conclude that: the association of mate consumption with upper aerodigestive tract cancer risk is unlikel y to result from insufficient control of confounding by critical expos ures. Owing to its high prevalence in Southern South America, mate dri nking may be linked to as many as 20% of all cases occurring in this r egion.