Fluid intake and incidence of renal cell carcinoma in UK women.

BACKGROUND: It has been suggested that the apparent protective effect of alcohol intake on renal cell carcinoma may be due to the diluting effect of carcinogens by a high total fluid intake. We assessed the association between intakes of total fluids and of specific beverages on the risk of renal cell carcinoma in a large prospective cohort of UK women. METHODS: Information on beverage consumption was obtained from a questionnaire sent ∼3 years after recruitment into the Million Women Study. Cox proportional hazards models were used to estimate relative risks (RRs) and 95% confidence intervals (CIs) for renal cell carcinoma associated with beverage consumption adjusted for age, region of residence, socioeconomic status, smoking, and body mass index. RESULTS: After an average of 5.2 years of follow-up, 588 cases of renal cell carcinoma were identified among 779,369 women. While alcohol intake was associated with a reduced risk of renal cell carcinoma (RR for ≥ 2 vs <1 drink per day: 0.76; 95% CI: 0.61-0.96; P for trend=0.02), there was no association with total fluid intake (RR for ≥ 12 vs <7 drinks per day: 1.15; 95% CI: 0.91-1.45; P for trend=0.3) or with intakes of specific beverages. CONCLUSIONS: The apparent protective effect of alcohol on the risk of renal cell carcinoma is unlikely to be related to a high fluid intake.