Breast Cancer Risk Increased by Menopausal Hormonal Therapy

Menopausal hormonal therapy (MHT), used to alleviate the symptoms of menopause, has been associated with an increased risk of breast cancer; but findings from previous studies have been inconsistent and lack long-term follow-up. A large, new meta-analysis of published and unpublished sources evaluated 108,647 postmenopausal women, who developed breast cancer, for history of MHT use to more clearly identify the link between MHT use and breast cancer.

A total of 51% of the patients included in this study had a history of MHT use. Patients began MHT at an average age of 50 years. Patients who were still taking MHT at the time of breast cancer diagnosis had been taking MHT for an average of 10 years, while women who were past users of MHT had an average treatment duration of 7 years. With the exception of vaginally inserted estrogen, any MHT use was associated with increased risk of breast cancer. Total risk depended on type of MHT. In women who did not use MHT, 20-year risk of breast cancer was 6.3%, while it increased to 8.3% with 5 years of estrogen and daily progesterone, 7.7% with 5 years of estrogen and intermittent progesterone, and 6.8% with 5 years of estrogen-only MHT. Prolonged duration of MHT use was also associated with an increased risk of breast cancer.

The authors concluded that use of MHT in women over the age of 50 is associated with a meaningful increase in cancer risk, particularly in patients receiving combined estrogen-progesterone products. This information may be useful in guiding selection of hormonal therapy in women with menopause.

To learn more about this study, visit Medscape Oncology.

Lancet. 2019 August 29. [Epub ahead of print.]

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