Some reports have shown that hormone replacement therapy, taken to relieve the effects of menopause, is associated with an increased risk for developing breast cancer. However, it now appears that hormone replacement therapy may not increase the risk for a recurrence (return) of breast cancer in postmenopausal survivors, according to a new study by Michigan researchers presenting at the May 2000 American Society of Clinical Oncology annual meeting in New Orleans.

Breast cancer is characterized by the presence of cancer cells in the tissue or ducts of the breast. Depending on the stage of disease (extent of the cancer at diagnosis), treatment options may include surgery, chemotherapy, radiation therapy, and/or hormone therapy. Often, surgery is followed by radiation therapy to the breast area, chemotherapy, and/or hormone therapy. Some breast cancers are

hormone receptor-positive and are thus more sensitive to the effects of hormones, such as estrogen and/or progesterone, which can help the cancer continue growing. For this reason, many women with breast cancer are treated with a hormone therapy called

tamoxifen (an anti-estrogen agent) to help prevent a recurrence (return) of the disease and to improve the chance of survival. However, it may be that this same hormonal sensitivity contributes to the increased risk for developing breast cancer that has been reported in association with long-term hormone replacement therapy.

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Hormone replacement therapy (HRT) is often used by postmenopausal women to control flushing and hot flashes, prevent osteoporosis, and delay any decline in mental function associated with menopause. Because of reports that long-term use of HRT may increase a woman’s risk for breast cancer, it would seem reasonable to believe that postmenopausal survivors of breast cancer who take HRT might be at an increased risk for developing a recurrence of their disease. However, this may not be the case, according to new findings presented by researchers from Michigan.

Researchers at the William Beaumont Hospital in Michigan evaluated 191 postmenopausal breast cancer survivors who had begun taking HRT with estrogen approximately 4 years after their cancer treatment. The average duration of HRT use was almost 3 years, and 25 women had taken HRT for more than 5 years. Sixty-five percent of the women had breast cancer that was hormone receptor-positive at the initial diagnosis. The outcomes of this group were compared with a group of women who had similar characteristics, but who did not take HRT. The results showed that 2% of those receiving HRT developed a recurrence in the breast, compared with 4.5% of those not receiving HRT. Recurrences developed in the opposite breast in 1.7% of the women taking HRT, and in 2.8% of those not taking HRT. Moreover, 5% of women taking HRT developed metastatic cancer (breast cancer that spread to other parts of the body), compared with 17% of those not taking HRT. Finally, the women receiving HRT had a better survival rate than the women not receiving HRT.

From these findings, the researchers concluded that HRT with estrogen in postmenopausal survivors of breast cancer dramatically relieved the effects of menopause and did not increase the rate of cancer recurrence. Postmenopausal women who are survivors of breast cancer and who are considering using HRT may wish to talk with their doctor about the risks and benefits of HRT, the potential for a cancer recurrence, and the prevention and treatment strategies currently available. (Proceedings of the American Society of Clinical Oncology Thirty-Sixth Annual Meeting, Vol 19, Abstract 2355, p 598a, 2000)

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