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December 2012 Ask the Expert: Fertility and Pregnancy

During the month of December, Living Beyond Breast Cancer experts Kutluk Oktay, MD, and Irene Su, MD, answered your questions about building a family after a breast cancer diagnosis, whether you are married or single.

Is it safe to get pregnant after breast cancer?

Can I adopt after having breast cancer?

What are the pregnancy rates after breast cancer?

What are the pros and cons of IVF?

Can I stop tamoxifen early to try and get pregnant? If I do stop it, how long should I be off it before I try to get pregnant?

Question: Is it safe to get pregnant after breast cancer?

Dr. Su:  Most women are advised to wait at least 2 to 3 years after a breast cancer diagnosis before becoming pregnant. Because the risk of cancer recurrence is higher earlier in survivorship, waiting to get pregnant is a way to prevent the difficult situation of finding a cancer recurrence early in pregnancy. 

There are no randomized research trials that focus on whether higher estrogen levels during pregnancy increase the risk of recurrence or death from breast cancer. But following large groups of young breast cancer survivors has shown that those women who choose to become pregnant do not appear to be at higher risk of recurrence or death.  Some studies suggest that breast cancer survivors who become pregnant may even have improved cancer outcomes. However, the women in these studies probably had improved cancer outcomes not because they were pregnant, but because they were healthier at the start (also known as a “healthy survivor bias”).   

Question: Can I adopt after having breast cancer?

Dr. Su: There are many ways to have a family after breast cancer, and adoption is a great option! Recently more adoption agencies have become open to helping cancer survivors have a family, and several online resources and books discuss adoption by cancer survivors. Other family planning options include attempting pregnancy naturally and using assisted reproductive treatments such as in vitro fertilization, egg freezing and gestational surrogacy.   

Question: What are the pregnancy rates after breast cancer?

Dr. Oktay: This depends on your age and whether and what type of chemotherapy you receive. Chemotherapy regimens that contain cyclophosphamide generally result in losing 10 years worth of egg reserve.

Women are born with a set number of eggs which they will spend until experiencing menopause. Because these egg numbers are very low by age 45-46, fertility pretty much ends at that age. Let’s say a woman received a chemotherapy regimen that contained cyclophosphamide at age 30. After chemotherapy, her egg reserve would be comparable to somebody at age 40 who has not had chemotherapy.

Also, what we call “egg quality” declines with age. While chemotherapy does not seem to reduce the quality of remaining eggs, fertility potential does decline because of declining egg quality as you age. This means that with age, the potential of an egg to be fertilized, develop into an embryo and become a healthy fetus is reduced. Hence, conception becomes more difficult in the late 30s to early 40s, and miscarriage rates increase.

In our research, we found that pregnancy rates are four  times lower in women undergoing in vitro fertilization after chemotherapy compared to those who did not receive chemotherapy. For example, live birth rates for women under age 30 can be as high as 60-65 percent but if they receive chemotherapy it drops to 15 percent or less per try. For a woman age 40 or older this chance is around 15-20 percent if no chemotherapy is received and 0-5 percent if chemotherapy is received.

This all means that if you receive chemotherapy and you have not yet experienced menopause, your likelihood of becoming pregnant is reduced. I recommend undergoing oocyte or embryo freezing before being exposed to chemotherapy. If you have already received chemotherapy, then you should not delay childbearing because you may experience menopause and infertility 10 years earlier than your peers. If you wait, your egg reserve and egg quality will drop with age.

A blood test called Anti-Mullerian Hormone as well as a test that counts antral follicle count, small follicles in your ovaries, can check your egg reserve. Both of these tests are more accurate when performed at least six months after you complete chemotherapy because ovaries go through a shock period after chemotherapy ends. If you had either test before you started chemotherapy, then your doctor can compare the before and after numbers to see if your egg reserve has changed. If you have a BRCA mutation, then ovarian reserve testing is even more important as you may have a lower egg reserve than women without the mutation.

For more information, please go to and select “educational resources” then “video topics.”

Question: What are the pros and cons of IVF?

Dr. Oktay: A major benefit of in vitro fertilization (IVF) is that it gives the highest success rates and can determine the number of embryos, as opposed to just using fertility medicines and having insemination or intercourse. A second benefit is that genetic conditions such as BRCA mutations can be tested in the embryos. IVF will shorten the time to pregnancy, which is important if you’ve had past chemotherapy and your egg reserve is already low. Of course with IVF there are multiple ultrasounds and blood draws and a transvaginal egg retrieval which may create some inconvenience, but most women do not find these disruptive.

Cons may include expense if your insurance does not cover the procedure and fertility medicines, and estrogen exposure if you have an estrogen-sensitive cancer. However, we have developed a way to perform IVF procedures without significantly increasing estrogen levels. A medicine called letrozole, which is used to lower estrogen levels in postmenopausal women with breast cancer, works like a fertility medicine in reproductive-age women. We combine this medicine with other injectable fertility medicines to keep estrogen levels in check. Our research shows that this method results in success rates comparable to that of standard IVF stimulation procedures and that recurrence rates are not increased.

For more information on the topic, please go to and select “educational resources” and then “video topics.”

Question: Can I stop tamoxifen early to try and get pregnant? If I do stop it, how long should I be off it before I try to get pregnant?

Dr. Oktay: Early discontinuation of tamoxifen must be discussed with your medical oncologist. Depending on your individual situation, your oncologist may allow you to interrupt tamoxifen after 2 years or, in some cases, delay the start so that you can have children without right away. However, all oncologists will tell you that the optimal benefit is achieved by 5 years of use. There is a recent study (ATLAS study) that even suggests better outcomes after 10 years, so many oncologists will be skeptical about short-cutting your treatment. Once stopped, tamoxifen will be cleared from your body within two menstrual cycles (around 40-60 days), and you may safely become pregnant. Some oncologists will recommend a longer wait period, but that is not usually necessary.

Tamoxifen does often result in ovarian cysts because it is an ovarian stimulant, and it may take few months before your ovaries return to normal. Hence there may be a natural delay in returning to a normal menstrual pattern.

If you are considering IVF treatments after tamoxifen, we generally start our treatments 40-60 days after the last dose of tamoxifen. It should also be noted that while tamoxifen is not safe during pregnancy, by the time you are pregnant and organ development begins in the fetus another four weeks will have passed since you ended tamoxifen. Hence a wait of 40-60 days before trying to become pregnant is more than sufficient.