April 5, 2005 -- New research suggests that some forms of menopausal hormone therapy may be safe for use by breast cancer survivors, but experts say too many safety questions remain to recommend that these women take hormones to relieve menopausal symptoms.
The Scandinavian study found no association between the use of menopausal hormone therapy and breast cancer recurrence in early-stage breast cancer survivors who took hormones for an average of four years.
The findings stand in sharp contrast to those of another major Swedish study on hormone therapy in breast cancer survivors published in December 2003. Researchers reported a threefold increase in cancer recurrences among survivors treated with hormones compared with survivors who did not take hormone therapy.
"The hope is that our new findings will stimulate discussion and research about whether certain types of hormone therapy are safe for this group of women."
Hormone therapy with estrogen alone in women who have had hysterectomies -- or estrogen plus progestin in those who haven't -- is considered to be the best treatment for hot flashes and other symptoms of menopause.
Its long-term use was linked to an increased risk of breast cancer, heart disease, and stroke in a widely publicized 2002 Women's Health Initiative (WHI) study. But limited use and low dosages specifically for the relief of menopausal symptoms is now generally considered to be safe for women with low cardiovascular and breast cancer risk.
The original intent of the two Swedish studies, begun prior to the publication of the WHI findings, was to assess the safety of long-term hormone therapy treatment in breast cancer survivors. The "Hormonal Therapy After Breast Cancer -- Is It Safe?" trial was stopped early after researchers reported the threefold increase in cancer recurrences among former patients who had taken hormones for just two years.
The newly reported Swedish trial is published in the April 6 issue of the Journal of the National Cancer Institute.
Although the two trials were similar, more women in the newly reported study got hormone therapy with estrogen alone. Also, those who took combination therapy with a progestin got a different schedule of dosing than routinely given to menopausal women. Instead of the hormones being given continuously and combined, as is routinely done in the U.S., progestin was given for just 14 days over three months.
The authors suggest that the differences in dosage and timing could explain why they found no increase in breast cancer recurrences in their treatment group. But they added that more study is needed to prove this.
"Although it is tempting to speculate that treatment regimens with estrogen and a minimum of [progestin] may be safe, the management of menopausal symptoms and quality of life for patients with breast cancer remains an important unsolved problem," Schoultz and colleagues write.
Hormone therapy expert Rowan T. Chlebowski, MD, tells WebMD there is growing evidence that short-term treatment with estrogen alone may be safe for breast cancer survivors. But he too says it is too soon to recommend any hormone therapy for this high-risk group. The only exception, he says, is women whose hot flashes and other menopausal symptoms are so severe that they are willing to take the risk.
Antidepressants, Chlebowski says, are the only treatment for menopausal symptoms that are widely considered to be safe for use by breast cancer survivors. He adds that they work about half as well as hormone therapy.
Alternatives to hormone therapy, such as black cohosh and soy-based treatments, work in similar ways to estrogen and therefore may carry the same risks.
In an editorial accompanying the study, the UCLA oncologist and reproductive biologist called for more studies to clarify the role of estrogen and progestin in promoting breast cancer.
"For breast cancer survivors, current evidence supports non-hormone-based interventions for [menopausal] symptom control in most circumstances," he writes. "The possibility that use of estrogen alone in symptomatic breast cancer survivors with a hysterectomy may represent an option with a favorable risk/benefit balance warrants further clinical attention."