Coffee consumption and bladder cancer risk.

The relation between consumption of regular and decaffeinated coffee and other methylxanthine-containing beverages and bladder cancer was analysed in a case-control study in two different areas of northern Italy (555 cases and 855 controls). The multivariate relative risk (RR) adjusted for smoking, occupation and sociodemographic variables for coffee drinkers versus non-drinkers was 1.3 (95% CI 1.0-1.8). The RR was 1.2 for one cup of coffee per day, 1.4 for two, 1.5 for three and 1.4 for four or more (P = 0.05). RRs for current drinkers were 1.5 (0.9-2.4) for decaffeinated coffee, 0.9 (0.6-1.2) for tea, and 0.6 (0.3-1.4) for cola. With reference to duration of consumption of coffee, RRs were 1.2 for less than 30 years or 1.4 for 30 years or more. Coffee-related RRs were higher in the older age group and in ex-smokers. Among 105 cases and 338 controls who had never smoked, RRs were 1.9 for one or two cups per day, 1.8 for three and 1.5 for four or more (trend not significant). A higher prevalence of coffee drinking among bladder cancer cases than controls was confirmed, with no clear dose-risk relation.