Abstract A042: History of infertility and risk of ovarian cancer in the women’s health initiative
Authors: Harris Holly , Lind Kimberly , Thomson Cynthia , Saquib Nazmus , Shadyab Aladdin , Schnatz Peter , Robles-Morales Rogelio , Qi Lihong , Strickler Howard , Roe Denise , Farland Leslie 
Published: March 2024

Abstract
Background: Given the consistent relationship between reproductive factors (e.g. parity) and risk of epithelial ovarian cancer, several studies have investigated the relation between infertility and ovarian cancer with conflicting results. Prior research has suggested differences in risk by specific infertility subgroups, which may have contributed to the conflicting findings. Further, few studies examined associations by ovarian cancer histotypes or were able to disentangle the influence of infertility vs. fertility treatment. Differences across studies could also have been influenced by different study populations (e.g., population-based vs. clinical population/registry of in-vitro fertilization [IVF]) and lack of consistent statistical control for important confounding factors including nulliparity, number of pregnancies, and age at first pregnancy. Finally, prior prospective studies have had limited follow-up, thus not capturing cancers that occur after menopause and which may have different risk factor profiles. Our objective was to determine the association between history of infertility and risk of postmenopausal ovarian cancer in a population that had not received treatment with IVF. Methods: We utilized the Women’s Health Initiative (n=114,761) with over 25 years of follow-up. At study baseline participants were asked whether they had ever tried to become pregnant for more than one year without becoming pregnant and whether a reason was found. Cox proportional hazards models were used to calculate the hazard ratios (HRs) of incident ovarian cancer comparing participants with a history of infertility to parous participants without infertility. Logistic regression models were used to calculate odds ratios (OR) for prevalent ovarian cancer at study baseline. Results: Approximately 16% of participants reported a history of infertility. 1,376 participants reported prevalent ovarian cancer at study baseline and 852 cases of ovarian cancer were diagnosed during study follow-up. In the prospective analyses, no statistically significant association was observed between infertility and risk of ovarian cancer overall (HR=1.16; 95% CI=0.98-1.37), by histotype, or with any specific infertility diagnoses. When prevalent ovarian cancer was examined, those reporting a history of infertility had a greater odds of ovarian cancer diagnosis (1.34; 95% CI=1.13-1.58) at WHI cohort baseline. This association was present for most infertility diagnoses with the strongest associations for hormonal/ovulatory (OR=1.97;95% CI=1.24-3.12), tubal/uterine factor (OR=1.63; 95% CI=1.15-2.31), and male factor (OR=1.71; 95% CI=1.19-2.47) infertility. Conclusions: We observed no significant association between infertility history and incident ovarian cancer in our population of postmenopausal participants. An association between infertility and ovarian cancer was present when prevalent ovarian cancer cases were examined, consistent with prior analyses that show stronger associations between ovarian cancer risk factors and ovarian cancer among younger women.
Citation Format: Holly Harris, Kimberly Lind, Cynthia Thomson, Nazmus Saquib, Aladdin Shadyab, Peter Schnatz, Rogelio Robles-Morales, Lihong Qi, Howard Strickler, Denise Roe, Leslie Farland. History of infertility and risk of ovarian cancer in the women’s health initiative [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr A042.