BackgroundAlthough the vast majority of lung cancer cases in women are caused by smoking, 9%-20% of cases occur in nonsmokers. Previous epidemiologic research on the relationship between lung cancer and diet has shown that fruit and vegetable consumption may confer a protective effect against lung cancer, while a diet rich in cholesterol and fat may increase risk.PurposeThe purpose of this case-control study was to examine the effects of a broad range of dietary factors on the risk of lung cancer in a population of nonsmoking white women 30–84 years of age.MethodsA telephone-administered questionnaire was used to determine and/or verify eligibility with regard to age, gender, race, and smoking status. In a second interview at the participant's home, a widely used food frequency questionnaire was filled out, and logistic regression was subsequently used to analyze the responses. We obtained dietary information on 429 case subjects who had a diagnosis of lung cancer reported to the Missouri Cancer Registry between June 1, 1986, and June 1, 1991, and 1021 control subjects. If a case subject had died or was too ill to be interviewed, next-of-kin familiar with the woman’s diet were interviewed instead. Of the 429 women with lung cancer, 211 (49%) had lung adenocarcinoma.ResultsA strongly increasing trend in lung cancer risk was observed with increased saturated fat consumption among these nonsmoking women; the relative risk was more than sixfold greater for the highest quintile of consumption than for the lowest quintile. The effect of saturated fat was more pronounced for adenocarcinoma than for other cell types. Weekly servings of beans and peas were significantly related to decreased lung cancer risk, while citrus fruit and juice showed a twofold increase in risk; this trend was also significantConclusionBy focusing on nonsmoking women with lung cancer, including a large number with adenocarcinoma, we observed a clear association with saturated fat consumption that may have been masked in earlier studies of lung cancer involving a high percentage of smokers. [J Natl Cancer Inst 85:1906–1916, 1993]