INTERNATIONAL RENAL-CELL CANCER STUDY .7. ROLE OF DIET

We investigated the role of diet in the etiology of renal cell cancer (RCC) in a multi-center, population-based case-control study conducted in Australia, Denmark, Sweden and the United States, using a shared p rotocol. A total of 1,185 incident histopathologically confirmed cases (698 men, 487 women) and 1,526 controls (915 men, 611 women) frequenc y-matched to cases by sex and age were included in the analyses. The a ssociation between RCC and diet was estimated by relative risks (RR) a nd 95% confidence intervals (CI) adjusted for age, sex, study center, body mass index and smoking. A statistically significant positive asso ciation was observed for total energy intake (RR = 1.7, 95% CI = 1.4-2 .2 for the highest vs. lowest quartile, p value for trend <0.00001), w hile the hypothesis that protein and fat are risk factors independent of energy was not supported. Fried meats were associated with increase d RCC risk, while vegetables and fruits were protective, with the stro ngest effect observed for the highest quartile of consumption of orang e/dark green vegetables but not vitamin C or beta carotene. Increased risk was associated with low intake (lowest decile) of vitamin E and m agnesium. We observed an apparent protective effect of alcohol confine d to women and probably due to chance. Our findings indicate an import ant role of nutrition in the development of RCC. The apparent positive association of energy intake with risk of RCC needs further investiga tion in a prospective cohort study to exclude the possible impact of d ifferences in recall between cases and controls. (C) 1996 Wiley-Liss, Inc.