The Risk of Post-menopausal Breast Cancer After Estrogen and Estrogen-Progestin Replacement
Hormone replacement therapy (HRT) in post-menopausal women is widely used for symptom relief and disease prevention. As sex hormones are involved in the etiology of breast cancer (BC), there is concern that hormone substitution after the menopause may increase BC risk. Accumulated epidemiological evidence shows that many years of recent or current HRT use leads to moderate excess risk of early stage BC, particularly in non-obese women. Results from our recently completed population-based study, including 3,345 cases of BC and 3,454 controls, aged 50–74 years, reveal clear and strong relationships between long-term intake of both estrogens (Es) and Es combined with progestins, seemingly confined to women with normal or lean body build. The results also suggest that the duration-dependent excess risk remains a long time after treatment cessation and that continuously/combined E-progestin treatment may be more adverse than those cyclically/combined. Our observations raise additional concern about the long-term safety of HRT and call for research efforts to define the safest possible HRT- regimens.
KeywordsEstrogen Osteoporosis Oncol Estradiol Progestin
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