A young woman recently came to the Mayo Clinic Cancer Center seeking a second opinion about treatment for her newly diagnosed breast cancer. She came to us in distress; she had seen a medical oncologist elsewhere who told her that she should plan a future with no pregnancies and no children of her own.
It was recommended that she begin treatment with chemotherapy followed by anti-estrogen medications to reduce her risk of breast cancer relapse. These treatments, she was told, would make it impossible for her to have children. She had wanted to have children soon and was hoping to hear a different message from us.
Breast cancer is the most common cancer diagnosed in women in the United States and worldwide. Some women are diagnosed with breast cancer at an age when they may be looking forward to having children. This can raise concerns about whether it is possible and safe for a woman to have children following treatment for breast cancer.
Young women with breast cancer typically have several specific concerns related to the impact of treatment on future motherhood. Their questions include:
- Is it possible for me to have a successful pregnancy after breast cancer treatment?
- Is it safe for me to get pregnant after breast cancer treatment? Will pregnancy cause my breast cancer to relapse? Will pregnancy be more difficult in some way due to exposure to chemotherapy and/or anti-estrogen therapy during breast cancer treatment?
- Is it safe for the baby if I get pregnant after breast cancer treatment? Will previous treatment be harmful in some way to the future fetus/newborn?
Each of these questions has been studied by breast cancer physicians. Let’s look at what is known:
Is it possible for me to have a successful pregnancy?
Here’s the good news: Many women have had successful pregnancies and have delivered healthy infants following adjuvant breast cancer treatments (chemotherapy and/or anti-estrogen therapies given to reduce relapse risk). However, it is not possible to know for sure whether a successful pregnancy in an individual breast cancer survivor is possible, because many factors determine the likelihood of successful pregnancy. These factors include:
- Maternal age
- Pre-treatment maternal fertility status
- Fertility status of the male partner
- Determination with which pregnancy is attempted
- Measures used to protect maternal fertility during treatment
Measures used to protect fertility include harvesting and freezing your eggs (oocyte cryopreservation) or an embryo (embryo cryopreservation). Some may even be able to remove and freeze an ovary and reimplant it at a later time (ovarian tissue cryopreservation). Learn about more fertility preservation options in this HealthSource post.
Therefore, while pregnancy following breast cancer treatment cannot be guaranteed, it is also true that breast cancer treatment does not necessarily make a future, successful pregnancy impossible.
Is it safe for me to get pregnant following breast cancer treatment?
More good news: Pregnancy following curative treatment for breast cancer does not increase the risk for relapse of the cancer, according to several studies.
In the past, breast cancer survivors were encouraged to wait at least two years following treatment before attempting pregnancy. More recent evidence suggests that timing has no impact on breast cancer relapse risk, whether the pregnancy occurs less than or more than two years after completing treatment.
Additionally, it was once supposed that pregnancy following treatment for estrogen receptor-expressing (“ER positive”) breast cancer would lead to a higher risk for cancer relapse due to the hormonal changes associated with pregnancy. However, pregnancy does not make it more likely to have relapse of ER positive breast cancer compared to women with ER positive cancers who do not subsequently become pregnant.
Is it safe for the baby if I get pregnant after breast cancer treatment?
As with every pregnancy, prenatal care is of the utmost importance. There are some additional concerns for pregnancy in breast cancer survivors: These pregnancies have been shown to result, on average, in infants with lower birth weight, smaller size for gestational age, greater likelihood of preterm delivery and greater likelihood of Cesarean section. However, babies born to women who have received chemotherapy to reduce their risk of relapse are most often healthy. These babies have no greater likelihood of genetic defects or post-partum illness than what is seen in babies born to women without a history of breast cancer.
It is recommended that breast cancer survivors NOT receive anti-estrogen therapy while trying to conceive or during pregnancy. It is not known if interrupting a course of relapse risk-reducing anti-estrogen therapy in order to complete a pregnancy will lead to greater risk for breast cancer relapse.
Hope for the future
We shared this information with the young woman and encouraged her to be optimistic that she can have a healthy baby after completing her breast cancer treatment.
She went on to have her breast cancer treatment with us, which included pre-operative chemotherapy and anti-HER2 therapy, and monthly injections of leuprolide to protect her fertility. At the time of her surgery all of the cancer in her breast was gone (known as complete pathologic response). She will complete post-operative anti-HER2 therapy in six months and sometime after that intends to attempt pregnancy.
Donald W. Northfelt, MD, MS, FACP
Dr. Northfelt is a medical oncologist at Mayo Clinic in Phoenix, Arizona where he serves as Associate Medical Director of the Breast Center. Dr. Northfelt is also the Arizona Site Director for the Mayo Clinic Center for Health Equity and Community Engagement Research. Follow him on Twitter @dnorthfelt.