The association of dietary fat and plant foods with endometrial cancer (United States).

OBJECTIVES: To examine the associations of dietary fat and selected plant foods with endometrial cancer in a population-based case-control study.

METHODS: Six hundred and seventy-nine incident cases of endometrial cancer diagnosed between 1985 and 1991, and 944 population-based controls completed a 98-item semi-quantitative food-frequency questionnaire and a detailed in-person interview which collected information on endometrial cancer risk factors. Logistic regression was used to estimate odds ratios (OR) and their 95% confidence intervals (CI) of endometrial cancer, adjusted for age, county, energy intake, hormone use, smoking and, in separate models, for body mass index (BMI: kg/m2).

RESULTS: Percent energy from fat was associated with an increased risk of endometrial cancer (highest quintile cf. lowest: OR = 1.8, 95% CI 1.3-2.6), with saturated and monounsaturated fats being the main contributors of risk. There was a stronger association between dietary fat and endometrial cancer among groups with higher circulating estrogen levels (i.e. women with higher BMI, users of unopposed estrogens, non-smokers, and younger age at menarche). Consumption of fruits or vegetables was inversely associated with endometrial cancer risk (highest quintile cf. lowest: OR = 0.65, 95% CI 0.46-0.93 and OR = 0.61, 95% CI 0.43-0.88, respectively). Further adjustment for BMI resulted in little or no attenuation of the ORs and associated CIs.

CONCLUSIONS: These results provide support for the theory that a low-fat, high-fruit and high-vegetable diet may reduce the risk of endometrial cancer, and that these dietary factors may act independently of the effect of BMI.