According to a recent article published in The Lancet, hormone replacement therapy following treatment for early breast cancer increases the risk of developing a cancer recurrence. This clinical trial was closed prematurely due to these results.1

Hormone replacement therapy (HRT) is often prescribed for women during menopause. Menopause is a natural phase of maturing womanhood, during which the ovaries produce significantly less estrogen, ovulation ceases and menstruation ends. For many women, menopause has uncomfortable side effects. Hot flashes, sleep disturbances, depression, mood swings and anxiety may affect the menopausal woman. Additionally, menopause may also be accompanied by increased urinary tract infections, incontinence, vaginal discomfort due to a lack of estrogen-based lubrication and decreased bone density. HRT has been effectively used to mitigate these side effects and is widely prescribed for women experiencing these unpleasant symptoms of menopause. Recent results from several clinical studies have demonstrated a correlation between the use of hormone therapy and an increase in the risk of developing breast cancer, and recently results from a clinical trial demonstrated an increase in death from breast cancer associated with the use of HRT.

2 HRT can contain estrogen alone, progesterone alone or a combination of the two hormones. Research continues in order to answers questions regarding different outcomes for patients who use specific combinations or single-agent HRT as well as duration of use.

Researchers from Sweden conducted a clinical trial that was initiated in 1997 to evaluate HRT in patients who had been treated for localized breast cancer (cancer that had not spread to distant sites in the body). This study included 434 patients, 219 of whom were prescribed HRT, and 215 of whom did not received HRT. One half of the patients had hormone receptor-positive breast cancer, (cancer that is stimulated to grow from exposure to estrogen), one quarter had hormone receptor-negative breast cancer (cancer that is not stimulated to grow from exposure to estrogen), and one quarter of patients did not have their receptor status known. After an average of approximately 2 years follow-up, patients treated with HRT had nearly 4 times the rate of a cancer recurrence (26 patients) compared to those not treated with HRT (7 patients). Patients who had initially been diagnosed with hormone receptor-positive cancer had a significantly higher rate of developing a cancer recurrence than patients diagnosed with hormone receptor-negative breast cancer. Furthermore, patients who had been treated with HRT prior to their diagnosis of breast cancer also had a significantly higher rate of the development of a cancer recurrence than those who had not received HRT prior to their diagnosis.

The researchers concluded that HRT given following the treatment for early breast cancer, or prior to the diagnosis of breast cancer, increases the risk of developing a recurrence. These results remain consistent with results from previous clinical trials that suggest an association between HRT and breast cancer. However, it is important for patients to speak with their healthcare provider about their individual benefits and risk with HRT.


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1.Holmberg L, Anderson H, for the HABITS Steering and Data Monitoring Committees, HABITS (Hormonal Replacement Therapy After Breast Cancer-is it Safe?), A Randomized Comparison:Trial Stopped.

The Lancet, Published Online February 3, 2004. .

2.Million Women Collaborators. Breast Cancer and Hormonal-Replacement Therapy in the Million Women Study.

The Lancet. 2003;362:419-427.

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