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August 2007 Issue

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'Shutting Down' Ovaries May Help Reduce Breast Cancer Recurrence in Premenopausal Women

By Amanda Harper
Published August 2007

Artificially inducing menopause may reduce breast cancer recurrence in premenopausal women with early-stage breast cancers.

A national phase-3 clinical trial, led locally by UC scientist Kathleen Havlin, MD, will determine whether medical suppression of ovulation combined with hormone therapy is better than hormone therapy alone for preventing breast cancer recurrence in premenopausal women.

Menopause is the natural cessation of menstruation and ovulation in women, which normally occurs between the ages of 45 and 50, and the related decline in levels of the natural female hormone estrogen.

Previous research has shown that estrogen promotes the growth of most types of breast cancer, and that reducing estrogen levels slows estrogen-dependent tumor growth in postmenopausal women.

Researchers will study 3,000 premenopausal women with “hormone receptor positive” breast cancer who have undergone surgery and completed any necessary chemotherapy.

“Even if there’s no evidence of residual tumor cells after treatment, we know a certain percentage of these women will experience recurrence later in life, so we need better strategies to reduce that risk,” explains Havlin, associate professor of internal medicine at UC and a medical oncologist at the UC Barrett Cancer Center at University Hospital.

The current standard of care for premenopausal women is five years of tamoxifen, an oral medication that blocks the effects of estrogen in the cells and minimizes estrogen in the body as a preventive measure. Each patient in the trial’s experimental group will choose her own ovulation suppression method: monthly injections with the drug triptorelin, ovary removal (oophorectomy) or six months of ovary irradiation.

Triptorelin resembles what is known as the body’s natural luteinizing hormone-releasing hormone. The drug affects the pituitary gland and reduces the amount of sex hormones (estrogen and testosterone) the body produces.

For this trial, participants will be randomized into one of three treatment groups to receive only tamoxifen, ovarian suppression plus tamoxifen, or ovarian suppression plus the drug exemestane for five years.

Exemestane belongs to a class of drugs known as aromatase inhibitors, which block the enzymes that produce estrogen.

“We know this drug can substantially reduce breast cancer recurrence in postmenopausal women with fewer side effects than tamoxifen,” adds Havlin. “But the only way we can give the drug to premenopausal women is by making them enter early menopause through ovarian suppression.

“We hope that by eliminating the potentially tumor-feeding estrogen supply in the body and then administering hormone therapy,” adds Havlin, “we can reduce breast cancer recurrence and improve the quality of life for this group of women.”

Women will be followed for five years and receive regular physical exams and blood tests every three to six months. Study patients should not be using hormonal birth control or have had any other hormone treatments six months prior to trial randomization.

For information on participating in this trial, sponsored by the International Breast Cancer Study Group, call (513) 584-2951.

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