Study Shows Estrogen Replacement Therapy Does Not Increase Risk to Breast Cancer Patients

In the first study of prolonged estrogen replacement therapy for patients successfully treated for breast cancer, researchers at The University of Texas M. D. Anderson Cancer Center have found that the hormone does not appear to increase the risk of recurrent or new cancers for former patients.

The results of study were published in the May 1 issue of the Journal of Clinical Oncology.

According to lead author Dr. Rena Vassilopoulou-Sellin, the study is significant in the ongoing debate regarding estrogen and sets the stage for expanding randomized clinical trials for examining the safety of estrogen replacement therapy for breast cancer patients. Dr. Sellin, an endocrinologist in the department of internal medicine specialties at M. D. Anderson, currently has under way the nation's first randomized clinical trial to study the safety of estrogen replacement therapy for menopausal women treated for breast cancer.

According to Dr. Sellin, the medical benefits of estrogen replacement therapy are well documented, though it has rarely been prescribed for women who have had breast cancer, due to a long-standing concern that the hormone might stimulate a recurrence of their cancer.

"The safety of estrogen replacement therapy for women with a history of breast cancer continues to stir debate because there is no scientific, prospective data to show whether or not estrogen increases the risk of recurrence. This lingering question of safety limits health care choices for breast cancer patients who may benefit," says Dr. Sellin. "In our research, we found no major risk for women with a history of breast cancer."

A total of 319 post-menopausal breast cancer patients were studied. Among the group of 39 women who received estrogen, one case of new breast cancer was reported.

Of the control group of 280 women - those who elected not to have the estrogen replacement therapy - 20 new or recurrent cases of cancer were found.

There were 14 patients who developed new or recurrent breast cancer at a median time of about 11 and one-half years after diagnosis, and six patients who developed other cancers at a median time of about 10 years after diagnosis.

The 319 post-menopausal women in the study share common characteristics. All the women had either Stage I or II breast cancer, had been disease free for at least two years and were all post-menopausal at the time of the study. In addition, they all had comparable tumor size, lymph node involvement, estrogen-receptor status and length of freedom from disease.

Because all the women had similar prognostic factors, the two groups were comparable in their risk for new or recurrent cancer, says Dr. Sellin.

"The results of this study and future randomized studies will improve a patient's quality of life," says Dr. Sellin. "We know the importance and value of estrogen in preventing heart disease, osteoporosis and many other physical symptoms, such as hot flashes and skin changes. With more women surviving breast cancer through earlier and better detection, we must have scientific data on the safety of estrogen for these women."

According to Dr. Sellin, more young women are being treated with chemotherapy for early-stage breast cancer, and many experience premature menopause brought on by the treatment.

"So many young breast cancer patients experience early menopause due to therapy and survive their disease for many years. We must be able to offer them safe options for bettering their health and quality of life for the long term," says Dr. Sellin. "The question is not whether they should or should not take estrogen, but whether their decision should be different from other women."

Dr. Sellin continues to recruit for the randomized clinical trial evaluating the safety of estrogen replacement therapy for postmenopausal women treated for breast cancer. The study is open to patients regardless of where they were treated for breast cancer.

For information on the study, please call 800-392-1611, Option 3.

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©2006 Texas Medical Center

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