Risk factors for lower urinary tract cancer: the role of total fluid consumption, nitrites and nitrosamines, and selected foods.

Many cases of lower urinary tract cancer cannot be attributed to the known risk factors of cigarette smoking and certain occupational chemical exposures. Data from a case-control study conducted on Oahu, Hawaii, from 1979 to 1986 were used to determine the role of several additional exposures in the etiology of lower urinary tract cancer, such as total fluid intake and dietary nitrites and nitrosamines, as well as intake of selected foods. A total of 195 male and 66 female lower urinary tract cancer cases of Caucasian and Japanese ancestry were matched to two population-based controls on age, sex, and race. Total fluid intake, and tap water in particular, showed a strong inverse dose-response relationship to cancer risk among women (odds ratio (OR) for highest to lowest quartile of total fluid intake = 0.3; trend P < 0.01).. This association was stronger in smokers than nonsmokers. Although fluid intake showed no overall association among men, the findings among smokers were suggestive of an effect similar to that found in women. Intake of dietary nitrites and nitrosamines was positively associated with risk in Japanese men (for nitrites, OR for highest to lowest tertile = 2.0; trend P = 0.05; for nitrosamines, OR for highest to lowest tertile = 3.0; trend P = 0.01). Consumption of processed meats, in particular bacon, sausage, and ham, was also significantly associated with increased risk in Japanese men. No other ethnic sex group exhibited this association with processed meats, although an effect was suggested for sausage in Japanese females and for bacon in Caucasian females. Unfortunately, it was not possible to determine whether these elevated risks were due to the fat, nitrite, or sodium content of the processed meats, or to the fact that they may have been fried.