Breast cancer touches the lives of almost all Americans. One in eight women will receive this diagnosis in their lifetime, making it the most common cancer in the U.S. While most new cases occur in those who are postmenopausal, 19% are in younger, reproductive-aged women. For breast cancer patients that have not yet completed childbearing, it can be overwhelming and stressful to juggle a new diagnosis and treatment options with concerns about future fertility and pregnancy.
During cancer treatment, chemotherapy can damage and deplete a woman’s eggs, making future conception more difficult. The risk of infertility depends on the type and dose of medication, and the age of the woman at the time of treatment. Furthermore, the likelihood of becoming pregnant is diminished by the aging that occurs during a delay in childbearing due to cancer treatment and recovery.
As a reproductive endocrinologist, I work with newly diagnosed cancer patients to discuss options for fertility preservation, so that each woman can achieve her family-building goals.

Fertility Preservation Methods
EGG FREEZING
Egg freezing is a process in which mature eggs are removed from the ovaries and frozen for potential use in the future. In order to freeze eggs prior to breast cancer treatment, a woman takes injectable medications to stimulate the ovaries for 10-14 days. The goal is to mature multiple eggs simultaneously, which will then be removed during an egg retrieval procedure and frozen in the embryology laboratory.
Since many forms of breast cancer are sensitive to estrogen, and a woman’s estrogen levels typically rise during an ovarian stimulation cycle, a medication called Letrozole can also be given to lower the body’s exposure to estrogen for the duration of the treatment.
When a woman decides to use frozen eggs in the future to create a pregnancy, they are thawed and fertilized with sperm to create embryos, which can then be transferred into the uterus and/or genetically tested. This process can be started very quickly and at any point in a woman’s menstrual cycle, so as not to delay breast cancer treatment. Many patients will complete their cycle in the time period between breast surgery and chemo/radiation.
EMBRYO FREEZING
Some women with partners will opt for embryo freezing prior to cancer treatment. The initial part of the process is the same as egg freezing, but after ovarian stimulation and egg retrieval, sperm is used to fertilize the eggs to create embryos. These embryos are grown in the laboratory and are typically frozen at the blastocyst (Day 5) stage. Blastocyst embryos can be tested for chromosomal abnormalities, or even for cancer-causing genes such as BRCA in women that have a genetic predisposition to cancer.
OVARIAN TISSUE CRYOPRESERVATION
Women who need to begin treatment urgently and do not have time for an egg or embryo freezing cycle, also have the option of ovarian tissue cryopreservation. Laparoscopic surgery is performed to remove part of one ovary, and this tissue is divided into pieces and frozen for the future. When a woman desires pregnancy, a piece of tissue is thawed and surgically transplanted onto her existing ovary. Some of these tissue grafts will become hormonally active and ovulate eggs in the future. This method was considered experimental until recently, but now over 130 babies have been born worldwide from ovarian tissue transplantation.
GNRH AGNONISTS
During chemotherapy treatment, medications called GnRH agonists can be given to suppress a woman’s hormones. This keeps the ovaries “quiet” in order to make eggs less susceptible to damage. This medication may reduce the chances of going into menopause during cancer treatment but is somewhat controversial. It is not a substitute for the other methods of fertility preservation listed above but can be given in addition to these treatments.

Pregnancy after Breast Cancer
PLANNING FOR PREGNANCY
Deciding when to become pregnant after cancer treatment is complex and influenced by many factors. The type of cancer, stage, and need for ongoing treatment all play a role in determining a safe time to conceive. It is always important for women to discuss these issues with their oncologist prior to proceeding with pregnancy. Most of the time, they are advised to wait at least a few years after the completion of treatment before trying to conceive. Sometimes, if a cancer is estrogen sensitive and long-term hormonal suppression is required, the recommendation may be to wait significantly longer.
GESTATIONAL CARRIER
For women with estrogen sensitive cancers and/or those taking long-term hormonal suppression to reduce recurrence risk, another option is to build their family with the help of a gestational carrier, also known as a surrogate. An embryo created prior to cancer treatment (or an embryo subsequently created with the prior frozen eggs) can be transferred into the uterus of a gestational carrier, who carries the pregnancy but has no biological relationship to the baby. This option allows for healthy, safe family building in women who would have a high risk for cancer recurrence in the setting of pregnancy.
OTHER OPTIONS
Women who do not preserve their fertility before cancer treatment also have other options for expanding their family. If they do not ultimately conceive on their own, they can use a donated egg or embryo to become pregnant, or can pursue adoption.
HOPE FOR FUTURE FAMILY BUILDING
A new breast cancer diagnosis can evoke feelings of fear and uncertainty about the future. This can be particularly difficult for premenopausal women that have not completed childbearing. Fortunately, women of reproductive age facing a breast cancer diagnosis have many options to make their dreams of motherhood a reality.
My patients who pursue egg and embryo freezing often report the experience to be hopeful and empowering during an otherwise challenging time. It is an honor to help each cancer patient to safely and successfully build her family.
Editor’s note: Dr. Laura Meyer is a reproductive endocrinologist with Reproductive Medicine Associates of Connecticut.