Coffee drinking and bladder cancer in Connecticut.

The association between coffee consumption and bladder cancer is investigated in a population-based case-control study carried out in Connecticut during 1978-1979. Measures of coffee consumption employed include total weekly cups, years of consumption, and more than seven cups per week, in addition to use frequencies of specific coffee types. After adjustment for age and cigarette smoking, a significant elevation in risk for consuming more than seven cups weekly was found for males (odds ratio = 1.5) but not for females (odds ratio = 1.0); there was also some evidence of a dose-response relationship in males. Among nonsmokers of both sexes combined, the odds ratio for more than seven cups per week was 1.9. Male smokers showed age- and smoking-adjusted odds ratios for coffee similar to those of male nonsmokers. Female smokers had a decreased risk for bladder cancer associated with increased coffee consumption which reflects the substantially lowered risk among older (65 years and over) smoking women who may constitute a selected resistant group; odds ratios among younger female smokers were close to 1.0. Males also showed elevated risks associated with consumption of regular (non-decaffeinated) and ground (noninstant) coffees. No relationship with duration of consumption was found.