Project Summary/AbstractInfertility burdens 10-15% of couples in the United States. Women suffering from infertility may be at increasedrisk of chronic diseases including cancer. A variety of pathways have been implicated in the associationbetween infertility and cancer risk including aberrant hormonal (e.g. excess androgens among women withovulatory infertility) and inflammatory environments (e.g. excess inflammation among women withendometriosis tubal factor infertility). Additionally the underlying etiology of the infertility may modify cancerrisk with some infertility diagnoses conferring higher cancer risk (e.g. endometriosis and ovarian cancer risk)and others conferring lower risk (e.g. ovulatory infertility and breast cancer). Research on the associationbetween infertility and cancer has been limited to mostly small clinical studies mechanistic studies andregistry studies with short durations of follow-up; all of which focus predominately on premenopausal cancerincidence and have been conducted among populations with limited racial/ethnic diversity. Moreoverinsufficient attention has been paid to differences in infertility diagnosis. Thus there are significant gaps in ourknowledge regarding the complex association between infertility and cancer risks. The proposed research willfocus on breast ovarian endometrial and colorectal cancers as these cancers have established hormonaland inflammatory risk factors and have some of the highest incidence and mortality. We will analyze the datacollected in the Womens Health Initiative (WHI)a large validated cohort that includes over 160000postmenopausal women with long follow-up duration (over 25 years) and strong racial/ethnic diversity withinthe sample population. Using these secondary data we will determine whether women who have experiencedinfertility have increased risk for specific cancers compared to parous women who never experienced infertilityand how this risk varies by infertility diagnosis. As approximately one in six women experience infertility andnearly 85% of cancers in women occur after menopause there are critical public health implications forunderstanding the relationship between infertility history and risk of these cancers among postmenopausalwomen.