Coffee and alcohol consumption and bladder cancer.

Epidemiological studies on coffee, alcohol and bladder cancer risk published up to 2007 were reviewed. Coffee drinkers have a moderately higher relative risk of bladder cancer compared to non-drinkers. The association may partly be due to residual confounding by smoking or dietary factors, but the interpretation remains open to discussion, although the absence of dose and duration-risk relations weighs against the presence of a causal association. Most studies of alcohol and bladder cancer found no association, with some studies finding a direct and other an inverse one. This again may be due to differential confounding effect of tobacco smoking--the major risk factor for bladder cancer--in various populations. Thus, epidemiological findings on the relation between alcohol drinking and bladder cancer exclude any meaningful association.