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(Last updated 5/27/99)
5/28/99
DRINKING WATER, EATING BROCCOLI REDUCE BLADDER-CANCER RISK
COLUMBUS, Ohio -- Drinking lots of fluids, especially water, and eating broccoli and cabbage can reduce men’s risk of bladder cancer, according to researchers at Ohio State and Harvard universities.
The study also determined that smoking can increase risk of bladder cancer by three to four times.
Researchers found that men who ate two or more half-cup servings of broccoli or one or more servings of cabbage per week had a 44 percent lower incidence of bladder cancer compared to men who ate less than one serving per week.
The study also revealed that men who drank the most fluids (12 or more cups per day) had a 51 percent lower incidence of developing bladder cancer than men who drank the least (less than five cups).
“This research pulled together three important pieces of a puzzle that, when taken together, give us several ways to prevent this disease,” said Steven Clinton, a co-author of the studies and leader of the Cancer Prevention and Control Program at Ohio State’s Comprehensive Cancer Center-Arthur G. James Cancer Hospital and Richard J. Solove Research Institute.
The implications of the study are easily summarized, he said. “Don’t smoke, drink fluids, and eat cruciferous vegetables, especially broccoli and cabbage.”
The study of bladder cancer and fluid intake, fruit and vegetable consumption, and smoking was taken from the same set of data but published as two journal articles. The study of fluids and smoking appeared in the May 6 issue of the New England Journal of Medicine, and the vegetable findings appeared in the April 7 issue of Journal of the National Cancer Institute.
The investigation, which involved Clinton, an associate professor of internal medicine, and teams of researchers at Harvard Medical School and the Harvard School of Public Health, examined a cohort of 48,000 men in the Health Professionals Follow-up Study. Over the past 10 years, 252 newly diagnosed cases of bladder cancer occurred within the group, enough to make this study statistically feasible.
Information on food and fluid intake was obtained using a baseline questionnaire given to the men in 1986 and follow-up questionnaires given in 1990 and 1994. The semi-quantitative questionnaires covered 131 food items, including 22 beverages.
Types of beverages studied were milk, fruit juice, coffee and tea, soda, water, and alcoholic beverage. The reduction in risk with fluid intake was most pronounced for water. Men who consumed 6 or more cups of water per day had a 49 percent lower incidence of bladder cancer compared to men who drank less than one cup of water per day.
Foods studied included nearly 40 kinds of vegetables and nearly 20 kinds of fruits. The foods were also grouped as yellow vegetables (e.g., carrots, yams, and yellow squash), green leafy vegetables (e.g., lettuce and spinach), cruciferous vegetables (which included broccoli, cabbage, cauliflower, Brussels sprouts, coleslaw, sauerkraut, and kale), and citrus fruits (oranges, orange juice, grapefruit and grapefruit juice).
Interestingly, when the researchers looked at fruits and vegetables together, they found no significant reduction in risk. Only the cruciferous vegetables showed a statistically significant reduction in risk, and only then with broccoli and cabbage.
Clinton viewed this finding as particularly important. “This gives us a wonderful foundation for future research,” he said. “Now, we can try to identify the specific agents that are involved in protection from bladder cancer. Perhaps we can purify these agents and use them in chemoprevention studies; perhaps we can grow cruciferous vegetables under different conditions to enhance the amount of these potentially beneficial substances and improve the nutritional value of these foods or make extracts or powders that can be used by those who are at particularly high risk of bladder cancer.”
Researchers have hypothesized a link between smoking and bladder cancer for a long time, said Clinton, “but this is the largest prospective study to assess the influence of smoking, and it showed a clear and strong three- to four-fold increase in risk in smokers compared to nonsmokers.”
Future work will include studying a cohort of nurses to see if the same factors apply in women.
“We haven’t examined the women’s group yet because bladder cancer occurs much less frequently in women,” he said, “and the nurse’s cohort hasn’t yet developed enough cases of the disease for this kind of analysis.”
Most cases of bladder cancer occur in smokers, and until the last three decades, women didn’t smoke as much as men. Clinton predicts that a study of women and bladder cancer using the nurse’s cohort will be possible over the next five years.
Bladder cancer is the fourth leading cancer to occur in men, and the ninth leading cause of cancer mortality in men. It is the eighth leading cancer in women.
- Contact: Steven Clinton, M.D., Ph.D., (614) 293-8396;
Clinton-1@medctr.osu.edu- Written by Darrell E. Ward, (614) 292-8456; Ward.25@osu.edu