Fluid intake and the risk of bladder cancer in men

Background Studies in animals have shown that the frequency of urination is inversely associated with the level of potential carcinogens in the urothe lium. In humans, an increase in total fluid intake may reduce contact time between carcinogens and urothelium by diluting urinary metabolites and incr easing the frequency of voiding. The data on fluid intake in relation to th e risk of bladder cancer are inconclusive. Methods We examined the relation between total Fluid intake and the risk of bladder cancer over a period of 10 years among 47,909 participants in the prospective Health Professionals Follow-up Study. There were 252 newly diag nosed cases of bladder cancer during the follow-up period, information on t otal fluid intake was derived from the reported frequency of consumption of the 22 types of beverages on the food-frequency questionnaire, which was c ompleted by each of the 47,909 participants who were free of cancer in 1986 . Logistic-regression analyses were performed to adjust for known and suspe cted risk factors for bladder cancer. Results Total daily fluid intake was inversely associated with the risk of bladder cancer; the multivariate relative risk was 0.51 (95 percent confide nce interval, 0.32 to 0.80) for the highest quintile of total daily fluid i ntake (>2531 mi per day) as compared with the lowest quintile (<1290 mi per day). The consumption of water contributed to a lower risk (relative risk, 0.49 [95 percent confidence interval, 0.28 to 0.86] for greater than or eq ual to 1440 mi [6 cups] per day vs. <240 mi [1 cup] per day), as did the co nsumption of other fluids (relative risk, 0.63 [95 percent confidence inter val, 0.39 to 0.99] for >1831 mi per day vs. <735 mi per day). Conclusions A high fluid intake is associated with a decreased risk of blad der cancer in men. (N Engl J Med 1999;340:1390-7.) (C) 1999, Massachusetts Medical Society.