Dietary factors in the risk of bladder cancer.

The relationship between selected dietary factors and the risk of bladder cancer was investigated in a case-control study conducted in northern Italy. The study included 163 cases and 181 controls who were hospitalized for acute, nonneoplastic or urinary tract diseases. The frequency of consumption of green vegetables and carrots was lower in the cases; thus, the estimated relative risks for the upper vs. the lower tertiles were 0.6 for green vegetables and 0.5 for carrots. Significant inverse trends in risk emerged with estimated carotenoid (as well as retinoid) intake. The apparent protection conveyed by vitamin A was stronger in current smokers. The risk of bladder cancer was not related to scores of fat and measures of alcohol consumption; the risk was elevated in coffee drinkers (although there was no tendency to rise with higher consumption), but it was reduced in tea drinkers. These findings were not explainable in terms of selection, information, or confounding bias. Thus, although available information is too uncertain for any precise definition of specific (micro)nutrients related to bladder cancer risk, the confirmation that several aspects of a less-affluent diet adversely affect the risk is still of interest in terms of a better understanding of bladder carcinogenesis.