Using the Medicine Clonidine To Treat Hot Flashes in Breast Cancer Patients Taking Tamoxifen

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The summary below is from the full report titled "Oral Clonidine in Postmenopausal Patients with Breast Cancer Experiencing Tamoxifen-Induced Hot Flashes: A University of Rochester Cancer Center Community Clinical Oncology Program Study." It is in the 16 May 2000 issue of Annals of Internal Medicine (volume 132, pages 788-793). The authors are K.J. Pandya, R.F. Raubertas, P.J. Flynn, H.E. Hynes, R.J. Rosenbluth, J.J. Kirshner, H.I. Pierce, V. Dragalin, and G.R. Morrow.

What is the problem and what is known about it so far?

Tamoxifen, an antiestrogen medicine commonly used for treating breast cancer, often causes hot flashes as a side effect. Hot flashes can be uncomfortable and disrupt a woman's normal activities, including sleep. Estrogen replacement hormones are used to treat hot flashes in women without breast cancer but cannot be used in breast cancer patients because they might cause the cancer to grow. Some studies have shown that clonidine, a nonhormonal medicine sometimes used to treat high blood pressure, can reduce hot flashes in women who have gone through natural menopause, but other studies have not shown that effect.

Why did the researchers do this particular study?

To find out if clonidine could reduce hot flashes in breast cancer patients who are taking tamoxifen.

Who was studied?

194 women who were taking tamoxifen as part of breast cancer treatment. All of the women were past menopause.

How was the study done?

Patients were randomly assigned to take either a clonidine pill once a day or a placebo pill that looked like the clonidine pill but contained no active ingredients. The women recorded in a diary the number, duration, and severity of each hot flash that occurred during the week before they started taking the pills and during the 4th, 8th, and 12th weeks of the study. The women also rated the overall quality of their life on a scale from 1 to 10 during each week that they wrote in their diaries.

What did the researchers find?

One hundred forty-nine women completed all 12 weeks of the study. Women who were taking clonidine reported a greater decrease in the frequency of hot flashes than women who were taking placebo at weeks 4, 8, and 12. However, statistical analysis showed that the decrease was only significantly different at 4 and 8 weeks. Women who took clonidine reported larger improvements in quality of life than women who took placebo, but these improvements were small. Forty-one percent of the women on clonidine reported increased difficulty sleeping compared with 21% of the women on placebo.

What were the limitations of the study?

This study was relatively small and lasted for only 12 weeks with 8 weeks of treatment. It is possible that the results would be different if the researchers had information on the 45 women who did not finish the study.

What are the implications of the study?

Clonidine taken by mouth may be helpful in treating hot flashes in women taking tamoxifen as part of breast cancer treatment.