ABSTRACT
Introduction ............................................................................................ 98 Descriptive Epidemiology...................................................................... 98 Cancer of the Bladder and Other Urinary Sites .................................... 99 Cancer of the Pancreas ......................................................................... 101 Cancer of the Colon and Rectum ......................................................... 102 Cancer of the Stomach and Upper Aerodigestive Tract ..................... 103 Cancer of the Breast.............................................................................. 104 Cancer of the Ovary ............................................................................. 104 Cancer at Other Sites ............................................................................ 104 Summary and Conclusions .................................................................. 105 Acknowledgments ................................................................................ 106 References ............................................................................................. 106
Studies on the relationship between coffee consumption and cancer risk have been mainly focused on cancers of the urinary bladder, pancreas, and colorectum, and most data refer to adult and elderly populations. The relationship between coffee and bladder cancer is controversial, although many case-control studies have been published over the last three decades. In most studies, compared to coffee nondrinkers, the odds ratio (OR) tends to be elevated in drinkers, but the excess risk is generally neither dose nor duration related. Thus, although coffee drinking may be considered a risk indicator of bladder cancer, a strong association can be excluded, and it is still unclear whether this indicator is causal or nonspecific and due to some bias or confounding. For pancreatic cancer, a possible positive association with coffee consumption was postulated in a report published in 1981; since then, however, most studies have shown no substantial association, and, thus, there is now substantial evidence that coffee is not related to pancreatic cancer risk. Overall evidence on the coffee-colorectal cancer relation suggests an inverse association: no consistent relationship was observed in five cohort studies, but most
case-control studies found OR below unity for colon and close to unity for rectal cancer. A plausible biological explanation has been given in terms of reduction of bile acids and neutral sterol secretion in the colon. For other cancer sites, including oral cavity, esophagus, stomach, liver, breast, ovary, kidney, and lymphoid neoplasms, data on the relation between coffee drinking and cancer risk are limited and generally inconsistent, but largely reassuring.
