To assess the role of diet and vitamin or mineral supplements in renal cell carcinoma (RCC) risk.
Mailed questionnaires were completed by 1279 (691 male and 588 female) newly diagnosed histologically confirmed RCC cases and 5370 (2696 male and 2674 female) population controls between 1994 and 1997 in eight Canadian provinces. Measurement included information on socioeconomic status, smoking habits, alcohol use, diet, and vitamin or mineral supplements. Odds ratios (ORs) and 95% confidence intervals (CIs) were derived through unconditional logistic regression.
A significant inverse association with RCC was observed with increasing total consumption of vegetables and vegetable juices for males and females combined. Increased consumption for two specific vegetable groups was inversely associated among females but not males: for females, the adjusted ORs for the highest quartile of consumption compared with the lowest were 0.5 (95% CI = 0.4-0.7) and 0.6 (95% CI = 0.4-0.8), p