A Prospective Investigation of Coffee Drinking and Bladder Cancer Incidence in the United States

Authors

• E Loftfield
• ND Freedman
• M Innoue-Choi
• BI Graubard
• R Sinha

Abstract

In 1991, coffee was classified as a Group 2B carcinogen, possibly carcinogenic to humans, by the International Agency for Research on Cancer (IARC) based on epidemiologic evidence suggesting a positive association with bladder cancer. In 2016, IARC downgraded this classification due, in part, to methodological concerns about reverse causality and confounding by cigarette smoking, which is often highly correlated with coffee drinking. Therefore, we assessed the association in 469,047 NIH-AARP Study participants who were cancer-free at baseline. During >15 years of follow-up, we identified 6012 incident bladder cancer cases. Multivariable-adjusted Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI), with coffee nondrinkers as the reference group. In our study, coffee drinking was positively associated with bladder cancer in models adjusted for age and sex (HR 4+ cups/day=1.91, 95% CI=1.70-2.14; P-trend

Scientific Focus Area: Epidemiology

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