High fluid intake appears to reduce bladder cancer risk

Although the study did not determine why increased fluid intake might be protective, Jiachen Zhou, M.B.B.S., M.P.H., a doctoral candidate in epidemiology at Brown University, hypothesized that the fluids may flush out potential carcinogens before they have the opportunity to cause tissue damage that could lead to bladder cancer.

Researchers evaluated the association between fluid intake and bladder cancer among 47,909 male participants in the prospective Health Professionals Follow-Up Study (HPFS) during a 22-year period. HPFS is a long-term study of male health professionals who were aged between 40 and 75 years at enrollment in 1986.

Participants answered a questionnaire about fluid intake every four years. Researchers found that high total fluid intake (more than 2,531 milliliters per day) was associated with a 24 percent reduced risk for bladder cancer among men.

Researchers first found an association between fluid intake and bladder cancer risk in this cohort 10 years ago. The association was present but weaker in the most recent study. Detailed analyses revealed the association was stronger among younger men, and this may explain the weakened association over time. The researchers also observed that the men drank fewer liquids, particularly water, as they aged.

Although he warned against generalizing these findings to the wider population, Zhou said that physicians should feel comfortable recommending that patients drink plenty of fluids.

The study was supported by grants from the National Institutes of Health.