Breast cancer risk factors and circulating anti-Müllerian hormone concentration in healthy premenopausal women

Context In a previous study we reported that anti-Müllerian hormone (AMH), a marker of ovarian reserve, is positively associated with breast cancer risk, consistent with other studies. Objective Assess whether risk factors for breast cancer are correlates of AMH concentration Design Cross-sectional Participants 3831 healthy premenopausal women (aged 21-57, 87% aged 35-49) Setting Ten cohort studies, general population Results Adjusting for age and cohort, we observed positive associations of AMH with age at menarche (p<0.0001) and parity (p=0.0008), and an inverse association with hysterectomy/partial oophorectomy (p=0.0008). Compared to women of normal weight (BMI 18.5-24.9 kg/m 2, AMH was lower (relative geometric mean difference 27%, p<0.0001) among women who were obese (BMI>30). Current oral contraceptive use and current/former smoking were associated with lower AMH concentration than never use (40% and 12% lower, respectively, p<0.0001). We observed higher AMH concentrations among women who had had a benign breast biopsy (15% higher, p=0.03), a surrogate for benign breast disease, an association that has not been reported. In analyses stratified by age (<40/≥40), associations of AMH with BMI and oral contraceptives were similar in younger and older women, while associations with the other factors (menarche, parity, hysterectomy/partial oophorectomy, smoking, and benign breast biopsy) were limited to women ≥40 (p-interaction<0.05). Conclusion This is the largest study of AMH and breast cancer risk factors among women from the general population (not presenting with infertility), and suggests that most of the associations are limited to women over 40, who are approaching menopause and whose AMH concentration is declining.