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Exploring the Safety of Pregnancy After Breast Cancer

It may surprise you to learn that in today’s world, nearly one in four new breast cancer cases occurs in women of childbearing age. What this means is that more and more women are facing questions involving pregnancy and fertility after being diagnosed.

Although this shift is causing researchers to pay more attention to these issues, it is no simple task to study pregnancy in women with breast cancer, or in women who have been treated for breast cancer. The difficulty is finding women with the same cancer status and fertility outcomes, who can be compared in randomized clinical trials.

Until recently, most doctors have worried pregnancy might spark hormonal changes in breast cancer survivors that could spur the disease's return, often counseling women against getting pregnant after they recover.

Although nearly all of the studies to date have focused on small groups of women, this limited research is beginning to answer some of the most crucial questions about the safety of pregnancy for women with a personal history of breast cancer and the safety of breast cancer treatment during pregnancy.

At the European Breast Cancer Conference held in March of 2010, the Royal College of Obstetricians and Gynecologists reported that pregnancy is safe for breast cancer survivors. They further advised that women should wait as long as five years after treatment before becoming pregnant. Their study additionally discovered that pregnancy may even have a protective effect for breast cancer survivors. The analysis suggested that women who became pregnant after a diagnosis of breast cancer had a 42 percent reduction in the risk of death compared with those who did not become pregnant.

The five year caution is meant to allow for assessment of long-term survival from the cancer, as well as to allow women taking Tamoxifen to complete their regime before becoming pregnant because of its known possible contribution to birth defects.

What the studies determined

Dr. Hatem Azim of the Institute Jules Bordet in Belgium who led the study, hypothesized that the relationship between hormones and breast cancer might be more complicated than doctors initially thought. “Estrogen is known to trigger breast cancer and women typically have more estrogen when they're pregnant. But very high doses of the hormone can also kill cancer cells,” Azim said.

“Other hormones that are elevated in pregnancy, like the one for breast-feeding, have been proven to protect against breast cancer. What we are seeing is only the tip of the iceberg," says Azim. "It's too simple to say that pregnancy stimulates hormones and that's bad for breast cancer."

Of the women studied, the findings indicate:

  • There was no apparent long-term increased risk of cancer recurrence or death in women who became pregnant after a breast cancer diagnosis.
  • Pregnancy did not appear to cause new cancers to develop.
  • Women who were diagnosed with breast cancer during pregnancy did as well in the long term as women with the same type and stage of cancer who were not pregnant when they were diagnosed.

Although this is very encouraging news, it is wise to keep in mind that most of the available information on pregnancy safety comes from only a few hundred women in all of them combined that are looking at past history. In these studies, researchers looked at the medical records of women who were still having their periods with a personal history of breast cancer. They then compared the outcomes of women who were pregnant at diagnosis, or who became pregnant after being diagnosed, to those of women who did not become pregnant.

The Waiting Game

For a woman already in her 30s who hopes to start a family or would like to have more than one child, finding the balance between waiting long enough to determine her overall health and the safety of pregnancy while worrying about her future fertility may seem daunting.

Although a younger patient may not experience menopause immediately, her reproductive life is definitely shortened. When you add the five years she needs to wait while being treated with Tamoxifen (and is not supposed to get pregnant), she may then experience menopause and infertility in combination with the added effects of age. It may very well be that patients even in their 20s are justified in looking at a fertility preservation strategy.*

As a general rule, for women not under the care of an infertility specialist, Tamoxifen should not be used if you are pregnant or trying to get pregnant. Your doctor might give you a pregnancy test to be sure you're not pregnant when you begin Tamoxifen treatment. Some general guidelines for this drug advise:

  • Do not try to get pregnant while you're taking Tamoxifen. Tamoxifen may cause damage to developing embryos. Use an effective non-hormonal barrier form of birth control (such as condoms or a diaphragm along with spermicide) while taking Tamoxifen as part of your breast cancer treatment. Continue to use barrier methods of birth control for two months after you finish Tamoxifen treatment, even if you don't have regular periods. Don't plan on trying to get pregnant until at least two months after Tamoxifen treatment is over.
  • If you're already pregnant, do not start taking Tamoxifen.
  • If you're taking Tamoxifen and you think you've become pregnant, stop taking the Tamoxifen and contact your doctor immediately.

It may be confusing when you hear that Tamoxifen can be used as a fertility drug but that it's harmful to developing embryos. As a fertility treatment, Tamoxifen is used to stimulate the ovaries to get more eggs ready for ovulation. At this juncture, the eggs have not yet been fertilized (and Tamoxifen does not damage unfertilized eggs). After the eggs are fertilized and become embryos, Tamoxifen may be harmful, since fertility has already been established.

Another compelling reason that women shouldn't get pregnant right after treatment, even if their prognosis favorable, has to do with the side effects of chemotherapy. Doctors often advise patients to wait at least six months before trying to get pregnant. Their reasoning is that there may be some eggs remaining in the ovaries that are damaged from chemotherapy, which could cause miscarriage and/or birth defects.

According to Dr. Eric Winer, director of the breast oncology center at the Dana-Farber Cancer Institute, "Breast cancer itself has no impact on getting pregnant; the difficult issue for pregnancy is related to the treatment for breast cancer."

Banking on the future

Because some breast cancer treatments, including chemotherapy and hormonal therapy, can cause temporary or permanent infertility in women who haven't gone through menopause, young women who want to have the option to get pregnant after treatment may want to consider:
  • Harvesting, freezing and storing eggs; one or more eggs can be fertilized and implanted after treatment is done.
  • Removing, freezing and storing ovarian tissue; this tissue can be put back in the body after treatment is done.

Study results presented at the 2010 annual meeting of the American Society for Reproductive Medicine (ASRM) found that young women who received fertility counseling before cancer treatment had fewer regrets and better overall quality of life after treatment compared to women who didn't get fertility counseling. This was true whether or not the women who got fertility counseling chose to see an infertility specialist or took fertility preservation steps before treatment.

When it comes to getting information about fertility risks and treatments, you may have to be your own advocate. Although by law physicians are required to let patients know about potential side effects of cancer treatment, including fertility problems, this information is often not discussed at any length.

Many oncologists and surgeons simply do not have sufficient training when it comes to fertility and cancer, so they often fail to refer patients to a specialist. A 2004 Dana Farber study found that 72 percent of female breast cancer patients discussed fertility concerns with a physician, but only 17 percent spoke with a fertility specialist.

If you are of an age where you will want to have children after you have completed treatment, be sure to ask your oncologist or consult with your local cancer center for a referral to a fertility specialist experienced in cancer care before you begin chemotherapy, since this is when your reproductive tissue is at its healthiest. You will want to be sure that the fertility clinic or specialist you choose is familiar with the latest protocols for fertility and cancer. They should regularly work with women in your situation. Be sure to find out what their pregnancy rate with in vitro fertilization (IVF), frozen embryos or tissue has been.

To find a clinic or determine a clinic's success rate, you can visit the Society for Assisted Reproductive Technology (SART), or the Centers for Disease Control (CDC), which offers success data for each state.

All things considered

If you are being treated for breast cancer or have a personal history of breast cancer and are considering having a baby now or in the future, here are some important questions to discuss with your doctor:
  • Do I feel well enough and strong enough to go through pregnancy and birth?
  • How long after treatment should I wait before trying to get pregnant?
  • Considering my age and the treatment I received, how likely am I to get pregnant?
  • Are there any treatments I'll have to stop if I want to get pregnant?
  • Are there any risks if I stop treatment to get pregnant?
  • Will I be able to continue treatment after I have a baby?
  • If I can't get pregnant, what kind of infertility treatments can I safely take?
  • Can I bank my eggs before chemotherapy in case I can't produce eggs after treatment?

Having children under any circumstances is a lifelong commitment. For a woman who has dealt with breast cancer, it is also a commitment she needs to fully explore and understand not only in terms of her current and future health, but the health and well-being of her child.

Women who are unable to get pregnant after treatment have every right to grieve. Having well-meaning friends and family making comments like, "You're alive, you should be happy!" certainly doesn’t help to resolve these feelings of despair. The emotions surrounding the inability to become pregnant for a woman wishing to have a family are as varied as the women facing this challenge.

Studies show that cancer survivors and infertile survivors have similar levels of grief, but in this instance the infertile survivor is getting the double whammy of dealing with both issues. Infertile cancer survivors, including those considering egg donation or adoption, may benefit from seeing a mental health professional, such as a psychologist or social worker, experienced in cancer care. Most hospitals have information about these sorts of services. For some women, online resources and support groups can also be useful.

Few experiences are more humbling and life affirming than the birth of a child. For a woman who has had breast cancer, the ability to once again have control over the possibility of reproduction is a giant step towards feeling healthy and normal. It is important, however, to take this step cautiously, armed with information pertinent to the individual’s medical condition and prognosis.

*Fertility preservation is the effort to help cancer patients retain their fertility, or ability to procreate. Current methods of fertility preservation include ovarian protection by GnRH agonists, cryopreservation of ovarian tissue, eggs or sperm, or of embryos after in vitro fertilization. The patient may also choose to use egg or sperm from a donor by third party reproduction rather than having biological children.

Article posted September, 2011.