The breast at perimenopause

Perimenopause, defined as the transition between regular menstrual cycles and confirmed menopause, is characterized by erratic hormonal secretions and metabolic disorders which can have potential consequences for breast health. During this period, benign breast diseases may worsen, adversely affecting quality of life and possibly increasing the risk of breast cancer. These aspects have implications for the clinical management of these women. Breast cancer has different characteristics and risk factors for women in premenopause, perimenopause and postmenopause. This narrative review analyzed available data on these risk factors during perimenopause, including the impact of hormonal contraception and menopause hormone therapy. Incidence and mortality, and subtypes of breast cancer differ in women according to the stage of menopause, ethnicity, the level of income of countries and public health resources. These inequalities in risk levels, breast cancer types and prognosis may affect screening and preventive strategies - an issue clinicians should be aware of. Among breast cancer survivors, the menopausal transition raises the question of a shift from tamoxifen, usually used in perimenopausal women, to aromatase inhibitors, indicated after menopause; the treatment may complicate the diagnosis of menopause. Women in the perimenopause may experience differences in the frequency and severity of endocrine therapy side effects.