Dietary factors and risk of uterine fibroids



 DESCRIPTION (provided by applicant): Uterine leiomyoma (UL) are the most common pelvic tumor in women of reproductive age. Despite the fact that these smooth muscle tumors are benign, UL are a significant public health problem, accounting for over 200,000 hysterectomies annually, and approximately 1 in 4 women will have a UL that comes to clinical attention. Despite the high morbidity and health care costs associated with UL, the etiology is not understood, and few modifiable, protective risk factors have been identified. Dietary factors may play a role in UL etiology due to their potential to modify endogenous hormones as well as their inflammatory effects. Hypothesis/Specific Aims: Our overall hypothesis is that intake and plasma biomarker levels of dietary components that influence endogenous hormonal and inflammatory response are associated with UL risk. Few studies have examined the association between dietary factors and UL. To our knowledge, only one prospective cohort has examined the association between dairy and dietary fat intake and UL observing a reduced risk of UL with increasing dairy consumption and associations with some fatty acids. In addition, no prospective studies have examined the association with vitamin D levels. Using prospective data we will evaluate the following aims: Aim 1. Evaluate the association between dietary fat and risk of incident uterine leiomyoma using data among 97,807 women in the NHSII cohort who completed a dietary assessment. In a subset of these women we will examine the association between circulating fatty acid levels and uterine leiomyoma. Aim 2. Dairy food intake is associated with risk of uterine leiomyoma. Aim 3. Vitamin D levels are associated with risk of uterine leiomyoma. Study Design: The proposed study consists of Nurses' Health Study II participants who completed a food frequency questionnaire (FFQ) about their usual diet in 1991. Follow-up FFQs were completed in 1995, 1999, 2003, and 2007. Quintiles or categories of dietary intake will be generated and Cox proportional hazards models will be used to estimate hazard ratios of UL incidence associated with each of the dietary factors. Among a subset of women with pre-diagnostic biomarkers, the association between plasma vitamin D and circulating fatty acids with UL risk will be assessed with logistic regression models. The presence of prospectively collected UL, dietary, and covariate data and stored blood samples, allows cost-efficient and valid consideration of the temporality of disease diagnosis - supporting the potential identification of modifiable risk factors.