Premature ovarian insufficiency and the risk of breast cancer

However, this extensive and very detailed guideline does not address the decreased risk of breast cancer (BCa) in women with POI.Among all the negative health implications of POI, the significantly lower risk of BCa is a benefit and treatment of POI should not interfere with this important favorable effect of POI.In a recent article, we presented the outcome of an extensive literature search regarding the relationship between the number of menstrual cycles (MCs) and the risk to develop breast cancer (BCa) (Coelingh Bennink et al., 2023).With average menarche at 11 years, average menopause at 51 years and a mean MC duration of 28 days, a woman experiences 13 MCs per year and 520 MCs during 40 years of menstrual cycling (2.5% BCa risk per year).The absolute lifetime risk of developing BCa in women in the United States has increased from 1 in 11 (9.1%) during 1975-1977 to 1 in 8 (13.0%) during 2017-2019, and women in the United Kingdom born after 1960 even have a risk of 1 in 7 (14.3%).Physiological variations in the frequency of MCs (menarche, menopause, pregnancies, lactation) and interference with MCs through genetic variations, pathological conditions (including POI), and pharmaceutical interventions reveal a strong direct relationship between the BCa risk and the lifetime number of MCs (Clavel-Chapelon, 2002; Collaborative Group on Hormonal Factors in Breast Cancer, 2012).