Background: The roles of several foods and beverages in the development of bladder cancer remain unclear.
Methods: We undertook a hospital-based case-control study at Aichi Cancer Center Hospital, Japan. Subjects included 124 men and women (bladder cancer cases) with newly diagnosed cancers of the renal pelvis (n = 5), ureter (n = 6) or bladder (n = 113) and 620 age- and sex-matched, cancer-free outpatients (controls) presenting at the hospital in the period from 1994 to 2000. Smoking-adjusted odds ratios (OR) were estimated to assess the strength of associations between self-reported intake of foods or drinks and bladder cancer risk, using conditional logistic models.
Results: We found a decreased risk in relation to frequent intake of green-yellow vegetables; the OR for the highest intake score compared with the lowest was 0.54 (95% confidence interval [CI] 0.29-0.99). The OR for carrot intake of >/=5 times/week compared with </=1-3 times/month was 0.41 (95% CI 0.16-1.01) and a decreasing risk with increasing consumption of green vegetables was also detected (P for trend = 0.063). Inverse associations between black tea, eggs and meat and risk were also suggested, whereas moderate drinkers of green tea (5-9 cups/day) showed an elevated risk. Coffee and milk consumption did not appear to exert any influence.
Conclusions: Those with an increased risk of bladder cancer, such as smokers, may benefit from increasing their consumption of green-yellow vegetables.