Abstract LB137: Ovulatory years prior to menopause and postmenopausal endogenous hormone levels

Abstract Background: Estimated lifetime ovulatory years (LOY) is the difference between ages at menopause and menarche subtracting time for events interrupting ovulation. We tested whether LOY influence sex-hormone levels in postmenopausal women not using hormone therapy. Methods: Hormones, including estradiol and testosterone, were measured in 1976 postmenopausal women from the Nurses’ Health Study in plasma collected in 1990. Effects of age, years since menopause, body mass index (BMI), smoking status, and hysterectomy on hormone levels were assessed by t-tests and ANOVA. Multivariable linear regression was used to assess associations between LOY and hormones adjusted for potential confounders and the trend in hormone levels per 5-year increases in LOY estimated. Results: Women in the sample averaged: 61.4 years old at blood draw, 11.0 years since menopause, with a BMI of 25.8 kg/m2. 17.5% had a hysterectomy and 13.8% were current smokers. These characteristics were associated with one or more hormone levels and included as adjustment variables. Each 5-year increase in LOY was associated with a 6.0% increase in testosterone (95% CI 3.3%, 8.7%) in all women. In women with above-average BMI, each 5-year increase in LOY was associated with a 7.3% (3.5%, 11.2%) increase in testosterone, a 6.9% (2.7%,11.3%) increase in estradiol, and a 6.9% (2.9%,10.9%) increase in estrone. Conclusion: Greater LOY is associated with higher testosterone in postmenopausal women as well as greater estradiol in those with above-average BMI. This may be due to an accumulation of functioning stromal and thecal cells from repeated ovulation and peripheral conversion of testosterone. Citation Format: Daniel W. Cramer, Allison F. Vitonis, Tianyi Huang, Amy L. Shafrir, Heather Eliassen, Robert L. Barbieri, Susan E. Hankinson. Ovulatory years prior to menopause and postmenopausal endogenous hormone levels [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB137.