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.
Final study results found women diagnosed with early-stage, hormone-receptor-negative breast cancer who were treated with Zoladex (chemical name: goserelin) in addition to chemotherapy before surgery were much less likely to be infertile after chemotherapy ended.
The research was published in the October 2018 issue of JNCI: Journal of the National Cancer Institute. Read the abstract of “Final Analysis of the Prevention of Early Menopause Study (POEMS)/SWOG Intergroup S0230.”
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.
Nearly twice as many women treated with Zoladex became pregnant
The final analysis of POEMS (Prevention of Early Menopause Study) included 218 premenopausal women diagnosed with early-stage, hormone-receptor-negative breast cancer between 2004 and 2011. All the women were treated chemotherapy before surgery (neoadjuvant chemotherapy) that included the medicine Cytoxan (chemical name: cyclophosphamide). Chemotherapy regimens that contain Cytoxan are more likely than others to cause infertility.
About half the women (105) were randomly assigned to get monthly injections of Zoladex while they were getting chemotherapy. The rest of the women (113) got only chemotherapy. The Zoladex injections started 1 week before the first chemotherapy dose.
After 5 years of follow-up, nearly twice as many women treated with Zoladex and chemotherapy became pregnant than women treated with just chemotherapy:
- 23.1% of women treated with Zoladex plus chemotherapy became pregnant.
- 12.2% of women treated with chemotherapy alone became pregnant.
Earlier results from POEMS presented in 2014 found that 22% of women treated with chemotherapy alone experienced ovarian failure, compared to 8% of women treated with Zoladex and chemotherapy. Because the final analysis was published as a brief communication, information on final ovarian failure rates were not included in the publication.
Can Zoladex improve survival?
The researchers also were surprised to see slightly better disease-free survival and overall survival rates in women treated with Zoladex and chemotherapy compared to women treated with chemotherapy alone.
Disease-free survival is how long the women lived without the cancer coming back. Overall survival is how long the women lived, with or without the cancer coming back.
After 5 years, disease-free survival rates were:
- 88% for women treated with Zoladex and chemotherapy
- 79% for women treated with chemotherapy alone
And 5-year overall survival rates were:
- 92% for women treated with Zoladex and chemotherapy
- 83% for women treated with chemotherapy alone
Still, neither of these differences were statistically significant, which means they could have been due to chance and not because of the difference in treatment. It’s possible that other risk factors are the reason for these differences. The researchers said more research is necessary to understand if Zoladex truly can help improve survival.
“These 5-year follow-up results confirm our initial findings," said lead researcher Halle Moore, M.D., associate professor of medicine at the Cleveland Clinic. "Goserelin protects the ovaries from the effects of chemotherapy, reducing the risk for early menopause. By getting these injections, more women became pregnant without negatively affecting their health or their chances of surviving …cancer."
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 woman 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.