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 suggests that women diagnosed with hormone-receptor-negative, early-stage 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 presented on May 31, 2014 at the American Society of Clinical Oncology 2014 Annual Meeting. Read the abstract of “Phase III trial (Prevention of Early Menopause Study [POEMS]-SWOG S0230) of LHRH analog during chemotherapy (CT) to reduce ovarian failure in early-stage, hormone-receptor-negative breast cancer: An international intergroup trial of SWOG, IBCSG, ECOG, and CALGB (Alliance).”
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.
This study included 257 women younger than 50 diagnosed with hormone-receptor-negative, early-stage breast cancer. All the women received 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 (126) were assigned to get monthly injections of Zoladex while they were getting chemotherapy. The rest of the women (131) got only chemotherapy. The Zoladex injections started one week before the first chemotherapy dose.
Two years after chemotherapy ended, 45% of the women who were treated with chemotherapy and didn’t get Zoladex had stopped menstruating or had higher levels of FSH (follicle stimulating hormone). Higher FSH levels mean less estrogen is being produced as well as a lower supply of eggs.
In comparison, only 20% of the women who got Zoladex in addition to chemotherapy had stopped menstruating or had higher FSH levels.
The researchers also compared pregnancy and birth rates between the two groups 2 years after chemotherapy ended:
- 21% of the women who got Zoladex with chemotherapy had become pregnant and 15% of them had given birth
- 11% of the women who didn’t get Zoladex with chemotherapy had become pregnant and 7% of them had given birth
The researchers also were surprised to see that the women who got Zoladex also had slightly better disease-free survival and overall survival rates compared to the women who didn’t get Zoladex. 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. Still, it’s possible that other risk factors are the reason for this difference. The researchers said more research is necessary to understand if Zoladex truly can help improve survival.
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.