A clear link between increased fluid intake and a decreased risk of bladder cancer has been shown in a paper in the New England Journal of Medicine by Dominique Michaud and her colleagues at the Department of Nutrition, Harvard School of Public Health (1999;340:1390-7).
In the prospective Health Professionals Follow up Study, researchers examined the relation between total fluid intake and the risk of bladder cancer over a period of 10 years among 47909 participants who were free of cancer in 1986.
Altogether, 252 cases of bladder cancer were newly diagnosed during the follow up period.
Information on total fluid intake was derived from the reported frequency of consumption of the 22 types of beverages on the food frequency questionnaire, which was completed by all participants.
American men who drank at least 11 glasses a day of all liquids had half the risk of developing the two types of bladder cancer found most commonly in developed countries—papillary and flat transitional cell carcinomas—than did men who drank five glasses or less.
Bladder cancer, which occurs in an estimated 319000 people a year world wide, is the fourth most common cancer among American men.
An editorial entitled “Prevention of Bladder Cancer” in the same issue of the New England Journal of Medicine said that cigarette smoking and occupational exposure to arylamines are thought to account for more than half of the cases of bladder cancer in the United States.
The results of the study by Dr Michaud and her colleagues are consistent with the urogenous contact hypothesis first proposed in 1974 by Oyasu and Hupp, and by Melicow, which associates the development of bladder cancer with prolonged exposure to carcinogens in urine.
Figure.
JILL CONNELLY/AP PHOTO
Drinking adequate liquids can halve the risk of bladder cancer