Cohort study of associations between reproductive factors and ovarian cancer risk by menopausal status and birth cohort in South Korea

Reproductive factors are associated with ovarian cancer risk, but their influence may differ across menopausal status and birth cohorts. A nationwide cohort study of 2,285,774 women aged 40 years or older in South Korea identified factors associated with ovarian cancer risk. Early menarche, later menopause and longer reproductive span were associated with higher ovarian cancer risk, whereas parity of 2 or more births was associated with lower risk across menopausal status groups. Breastfeeding duration and oral contraceptive use were associated with lower risk only among premenopausal women, and the inverse association for parity was attenuated in the 1960s birth cohort. The authors conclude that the findings of this study support the need for tailored prevention strategies in aging, low-fertility societies.