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DURHAM, N.C. -- Researchers at Duke University Medical Center have shown that ovarian hormone levels may predict which women are likely to become infertile after chemotherapy to treat breast cancer.

Their findings may ultimately enable physicians to identify at-risk breast cancer patients who could benefit from fertility-preserving treatments, said Carey Anders, M.D., lead author of the study.

Infertility is a common side effect of cancer therapies such as chemotherapy and radiation, because such therapies can damage rapidly dividing cells such as granulosa cells in the ovaries. No method exists to identify which women are at greatest risk of premature ovarian failure, defined as the loss of menses for more than six months. Often times, the condition is permanent.

In the current study, the researchers showed that women who developed premature ovarian failure had lower levels of the ovarian hormone inhibin A before chemotherapy and six months after chemotherapy had ended. Their levels of inhibin B were also lower six months after chemotherapy.

Conversely, women who resumed menses after treatment had higher levels of inhibin A before receiving chemotherapy and six months afterward. The same effects were seen with another ovarian hormone, estradiol.

Results of the study will be presented Thursday, Dec. 8, 2005, at the annual San Antonio Breast Cancer Symposium.

"Identifying hormones that predict the likelihood of premature ovarian failure will enable us to take action to prevent such damage before cancer treatments begin," said Anders, a hematology-oncology fellow at Duke. "The development of a hormonal marker will help identify women at risk for premature ovarian failure and foster earlier referrals to infertility specialists."

Among the treatments being studied to preserve ovarian function are drugs called gonadotropin releasing hormone analogs. Such drugs protect the ovaries by temporarily halting ovarian function. Chemotherapy targets rapidly dividing cells, so halting ovarian activity prevents chemotherapy from targeting the ovaries. Fertility specialists are also studying the use of ovarian cryopreservation – extracting and freezing eggs -- and in vitro fertilization as tools to preserve fertility among cancer patients.

"Developing predictive markers of premature ovarian failure will be invaluable to premenopausal women and their clinicians as they face therapy for early-stage breast cancer," said Anders.

The Duke study included a total of 30 women whose hormone levels were measured at various points before, during and after chemotherapy treatment for early-stage breast cancer. Chemotherapy halted menses for some women but not for others, the study showed.

In the study, women who developed premature ovarian failure had lower levels of inhibin A both before treatment (57.4 pg/mL) and afterward (2.5 pg/mL). Women who maintained their menses had higher levels of inhibin A before treatment (83.4 pg/mL) and showed less dramatic losses afterward (22.6). Anders plans to study a total of 120 women to validate her initial findings, but the current findings provide a promising marker for premature ovarian failure, she said.

Co-authors of the study include Stacey A. Snyder, Wendy Demark-Wahnefried, Ph.D., Renee Welch, P. Kelley Marcom, M.D., Heather Shaw, M.D., Stephen Chui, M.D., and senior author Kimberly Blackwell, M.D.