Many women diagnosed with breast cancer, especially younger women, are concerned about their ability to have children after treatment. Some breast cancer treatments can cause temporary infertility or make it harder to get pregnant after treatment ends. Other treatments, especially certain chemotherapy regimens, can cause early menopause and infertility.
A study shows that premenopausal women diagnosed with hormone-receptor-negative, early-stage breast cancer who were treated with Zoladex (chemical name: goserelin) along with chemotherapy after surgery were much less likely to be infertile after chemotherapy ended than women who got chemotherapy without Zoladex.
The research was published in the March 5, 2015 issue of The New England Journal of Medicine. Read the abstract of ”Goserelin for Ovarian Protection during Breast-Cancer Adjuvant Chemotherapy.”
Zoladex is a GnRh (gonadotropin-releasing hormone) agonist. GnRH agonists are hormones that block GnRH, a hormone made in the brain that tells the ovaries to get ready for ovulation. Ovulation happens when a mature egg is released from the ovary, ready to be fertilized. When GnRH is blocked, no ovulation occurs. So Zoladex causes the ovaries to temporarily shut down. By doing this while a woman is being treated with chemotherapy, the goal is to help protect the eggs from the chemotherapy medicine.
Doctors call treatments given after surgery to reduce the risk of the cancer coming back (recurrence) adjuvant treatments. Chemotherapy, hormonal therapy, and targeted therapy are common adjuvant treatments for breast cancer.
The study included 218 premenopausal women ages 18 to 49 diagnosed with early-stage, hormone-receptor-negative breast cancer. The women were randomly assigned to receive either:
- Zoladex plus chemotherapy
- chemotherapy alone
The women who were treated with Zoladex got it every 4 weeks, starting 1 week before the first round of chemotherapy. Most of the women (91%) received anthracycline-based chemotherapy.
None of the women had taken any type of hormonal therapy, birth control pills, or hormone replacement therapy in the month before the study started.
The researchers were looking for answers to several questions:
- How many women had ovarian failure 2 years after chemotherapy? Ovarian failure meant that a woman hadn’t had a period in the past 6 months and had follicle-stimulating hormone levels in the postmenopausal range. Follicle-stimulating hormone stimulates ovulation. If your ovaries are in menopause, they no longer respond to follicle-stimulating hormone and your brain reacts by sending out more hormone. So higher follicle-stimulating hormone levels indicate menopause.
- How many women had successful pregnancies?
- What were the disease-free and overall survival rates? Disease-free survival is how long a woman lives without the cancer coming back. Overall survival is how long a woman lives, with or without the cancer coming back.
After 2 years, the researchers looked at information from 135 of the women in the study. This means that the researchers were missing information on 83 (nearly 40%) of the women in the study.
The results showed a big difference in ovarian failure rates between the two groups:
- 8% of the women who got Zoladex and chemotherapy had ovarian failure
- 22% of the women who got chemotherapy alone had ovarian failure
There was also a big difference in pregnancy rates after treatment:
- 21% of the women who got Zoladex and chemotherapy had at least one pregnancy; 18 babies were born to women in this group
- 11% of the women who got chemotherapy alone had at least one pregnancy; 12 babies were born to women in this group
About 24% of the women who got Zoladex and chemotherapy tried to get pregnant after treatment compared to 16% of women who got only chemotherapy.
Women in the Zoladex group also had slightly higher disease-free survival rates (89% compared to 78%) and overall survival rates (92% compared to 82%). Still, it’s possible that other risk factors are the reason for these differences. More research is needed to understand if Zoladex can truly help improve survival.
While the missing information from about 40% of the women in the study does weaken the strength of the results, the findings are still very encouraging. This is also the second study to show that suppressing ovarian function during chemotherapy can help preserve fertility.
If you’re a premenopausal woman who’s been diagnosed with early-stage, hormone-receptor-NEGATIVE breast cancer and are concerned about preserving your fertility, you might want to talk to your doctor about this study. It may be possible that you can be given Zoladex in addition to your chemotherapy to shut down your ovaries and help preserve your fertility.
If you’re a premenopausal women who’s been diagnosed with early-stage, hormone-receptor-POSITIVE breast cancer, unfortunately this study doesn’t apply to you. Still, there are other options available to you, including harvesting mature eggs from your ovaries before treatment starts. The most important thing to do is to talk to your doctor about fertility as you’re planning your treatment. You also can ask for a referral to a fertility specialist for counseling before treatment begins.
For more information, visit the Breastcancer.org pages on Fertility and Pregnancy Issues During and After Breast Cancer.