Among 35,192 postmenopausal, predominantly white women in Iowa age 55-
69 years and free of cancer, we collected baseline history, dietary in
formation, and anthropometric data by mail in 1986. We ascertained the
8-year incidence (62 new cases) of renal cell carcinoma using the Iow
a Surveillance, Epidemiology, and End Results (SEER) register, the Nat
ional Death Index, and mail follow up. Risk factors for renal cell car
cinoma included increasing age, increasing weight (either current, max
imum adult weight, or weight at ages 18, 30, or 50 years), greater wai
st-to-hip ratio, and a history of blood transfusion. Total dietary cal
cium was associated independently with a reduced risk of renal cell ca
rcinoma. No other dietary micro or macronutrients or food groups were
predictive of the development of renal cell carcinoma. Other previousl
y identified risk factors were not confirmed: most notably, there was
no increased risk from a history of hypertension, after adjustment for
diuretic use. History of ever-use of diuretics was associated with a
twofold increased risk of renal cancer, although the strength of assoc
iation was markedly reduced after adjustment for age, weight, waist-to
-hip ratio, and calcium intake.