Ovarian function and disease risk

The role of ovarian function is reviewed with reference to breast, female genital tract neoplasms, and ischaemic heart disease. The risk of breast cancer is increased by early menarche, late menopause and regular menstrual cycles. The associations observed are modest, but are still consistent with an unfavourable effect of ovarian function on breast cancer risk. Ovarian cancer is possibly related to early menarche and associated with late menopause. A protective effect has been observed with irregular menstrual cycles and oral contraceptive use. Ovulation has been related to ovarian cancer risk in terms of the multistage model of carcinogenesis, although the biological process appears more complex. Endometrial cancer risk is increased by early menarche, late menopause, nulliparity, and — in premenopausal women — obesity. The risk of endometrial cancer is increased by oestrogens and decreased by progestins. Thus, anovulation increases endometrial cancer risk. Ischaemic heart disease is not related to age at menarche, but is associated with early menopause. Irregular menstrual cycles may also increase the risk. The impact of ovulation on cardiovascular disease should be viewed with reference to the different role of oestrogens (protective) and progestins (possible adverse). Other hormone imbalances (e.g., hyperandrogenaemia) may also be related to ischaemic heart diseases.