Hormones and Breast Cancer

A major stumbling block to the use of estrogen replacement in women is the concern that it will increase the risk of breast cancer.  It has been recommended that hormone replacement be withheld from women with increased risk of breast cancer based on personal or family history, lifestyle, increased breast density or fibrocystic breast disease, and that hormone replacement should be offered for the shortest possible time after menopause. This belief results in many women being deprived of the benefits of hormone replacement that may extend over years.

Research on the incidence of breast cancer in estrogen replacement therapy offers uncertain conclusions.  Some studies have implicated non-human identical estrogen as a cause of breast cancer.  Other studies have demonstrated increased risk from progestins, or non-human identical progesterone, given with the estrogen.

A large French study, released in 2007, demonstrated NO increase in breast cancer incidence when human-identical progesterone was given with estrogen.  A very recent study from the Women’s Health Initiative revealed a REDUCED rate of breast cancer in women given estrogens for 5.9 years, with that lower rate persisting over more than 10 years of follow-up.

There is no definitive conclusion about breast cancer risk and hormone replacement therapy.   We believe that hormone replacement therapy may be carefully initiated in post-menopausal women, using low effective doses, and maintained indefinitely, provided the women are closely monitored.  The benefits of hormone replacement are too substantial to be denied to the majority of women.