When a pregnant woman develops breast cancer, it is often diagnosed at a later stage than it is in women who are not pregnant. It is also more likely to have spread to the lymph nodes. This is partly because during pregnancy hormone changes cause a woman’s breasts to get larger, tender, and lumpy. This can make it harder for you or your doctor to notice a lump in your breasts until it gets quite large. Mammograms are also harder for doctors to read during pregnancy because the breast tissue becomes denser. The early changes caused by cancer are easily mistaken for or hidden by the normal changes that happen with pregnancy.
Mammograms can detect most of the cancers that start during pregnancy. But screening may be postponed because some patients (and even doctors) worry about the safety of doing a mammogram during pregnancy. But it is fairly safe to have a mammogram during pregnancy. The amount of radiation needed for a mammogram is small. And the radiation is focused on the breast so that most of it does not reach other parts of the body. For extra protection, a lead shield is placed over the lower part of the belly to stop radiation from reaching the womb. Still, scientists can’t be certain about the effects of even a small dose of radiation on an unborn baby. If your doctor does not believe you need to have your mammogram right away, it may be best to wait. Other imaging tests that do not use radiation, such as breast ultrasound, may be used instead. These are thought to be safe alternatives to mammograms during pregnancy.
Even during pregnancy, early detection is an important part of breast health. Talk to your doctor or nurse about breast exams and the best time for your next mammogram, especially if you are age 40 or older, or if you or your doctor notices a change in how your breasts look or feel. As always, if you find any lump or change in your breasts, tell your doctor or nurse right away.
Breast cancer diagnosis and staging during pregnancy
Biopsy
A new lump or abnormal imaging test result may cause concern, but a biopsy is needed to find out if it is breast cancer. During a biopsy a piece of tissue is taken from the area of concern. This is usually done either using a long, hollow needle or through a small surgical incision (cut). A breast biopsy during pregnancy can usually be done as an outpatient procedure. The doctor uses medicine to numb just the area of the breast involved in the biopsy. This causes little risk to the fetus. But a biopsy can be done under general anesthesia (where drugs are used to put the patient into a deep sleep) if needed, with only a small risk to the fetus.
You can get more details on different types of breast biopsies in our document called For Women Facing a Breast Biopsy.
Tests to learn the cancer stage
If breast cancer is found, other tests may be needed to find out if cancer cells have spread within the breast or to other parts of the body. This process is called staging. Staging tests are very important for pregnant women with breast cancer because their cancers tend to be found at a more advanced stage (the tumor is likely to be bigger and to have spread beyond the breast). Which staging tests may be needed depends on your case.
Keep in mind that the fetus is not exposed to radiation with tests like ultrasound and magnetic resonance imaging (MRI) scans. Overall, these tests are thought to be safe and can be used if they are important to your care. But the contrast material (dye) sometimes used in MRI crosses the placenta, the organ that connects the mother to the fetus. It has been linked with fetal abnormalities in lab animals. For this reason, an MRI that uses contrast dye is not recommended during pregnancy. But an MRI without contrast can be used if needed.
Chest x-rays are sometimes needed to help make treatment decisions. They use a small amount of radiation. They are thought to be safe for pregnant women when the belly is shielded.
Other tests, such as bone scans or computed tomography (CT) scans of the chest, abdomen (belly), or pelvis, are more likely to expose the fetus to radiation. These tests are not often needed, especially if the cancer is thought to be just in the breast. In rare cases when these scans are needed, doctors can adjust the way the test is done to limit the amount of radiation the fetus is exposed to.
In very few cases, the cancer has reached the placenta (the organ that connects the mother to the fetus). This could affect the amount of nutrition the fetus gets from the mother, but there are no reported cases of breast cancer being transferred from the mother to the fetus.
Breast cancer treatment during pregnancy
If breast cancer is found during pregnancy, the type and timing of treatment depends on many things, such as:
- The size of the tumor
- Where the tumor is
- Whether and how far the cancer has spread
- How far along the pregnancy is
- What the woman prefers
Treating a pregnant woman with breast cancer has the same goals as treating a non-pregnant woman: control the cancer in the place where it started and keep it from spreading. But protecting a growing baby may make reaching these goals more complex.
If a pregnant woman needs chemotherapy, hormone therapy, or radiation to treat breast cancer, she may be asked to think about ending the pregnancy. This is because these treatments may harm the fetus. It is easier to treat a woman who is not pregnant because there is no fear of harming the fetus. But no studies have proven that ending a pregnancy in order to have cancer treatment improves the woman’s prognosis (outlook for survival). Still, this is an option that may be discussed when looking at all the treatment choices available.
Surgery
When possible, surgery is the first treatment for any woman with breast cancer, including those who are pregnant. Removing the tumor (lumpectomy) or the entire breast (mastectomy), and/or taking out the lymph nodes under the arm carry little risk to the fetus. But there are certain times in pregnancy when anesthesia (the drugs used to make you sleep for surgery) may be riskier for the fetus. Many doctors, such as a high-risk obstetrician, a surgeon, and an anesthesiologist will need to work together to decide the best time during pregnancy to do surgery. If the surgery is done later in the pregnancy, the obstetrician may be there just in case there are any problems with the baby during surgery. Together, these doctors will decide which drugs and techniques are the safest for both the mother and the baby.
Mastectomy can often be used as the first treatment for early stage cancers. Lymph nodes in the armpit may also need to be taken out if there is suspicion that the cancer has spread there. Depending on the how far along you are in pregnancy and your cancer stage, your doctor may not be able to do a sentinel lymph node biopsy (SNLB). This is when tracers and dye are used to pinpoint the nodes most likely to contain cancer cells. SNLB allows the doctor to remove of fewer nodes. But there is concern that the radioactive tracer used for SNLB may affect the fetus if used during times organs are growing quickly. More research is needed on this.
Depending on the cancer’s stage, a woman may get more treatment such as chemotherapy, radiation, and/or hormone therapy after surgery to help lower the risk of the cancer coming back. This is called adjuvant treatment.
Women who have breast-saving surgery, like lumpectomy, often need radiation therapy afterward to reduce the chance that the cancer will come back. The need for radiation is an important issue for pregnant women when choosing which surgery to have. Radiation could affect the fetus if given during the pregnancy, so it is not used until after the birth. Doctors don’t know how this delay may affect a woman’s risk of the cancer coming back. Cancer found in the third trimester may involve very little delay in radiation treatments, so there would likely be no effect on outcome. And a woman who will be getting chemotherapy before radiation may have little or no delay in her radiation treatments. But cancers found early in the pregnancy may mean a longer delay in starting radiation. Treatment must always be considered on a case-by-case basis.
Chemotherapy
Chemotherapy, which is also called “chemo,” may be used along with surgery (as an adjuvant treatment) for some earlier stages of breast cancer. It also may be used by itself for more advanced cancers.
Chemo usually is not given during the first 3 months of pregnancy (the first trimester). This is because most of the fetus’s internal organs develop during this time. The risk of miscarriage (losing the baby) is also the greatest during the first trimester. The safety of chemo during this time has not been studied because of concerns about damage to the fetus.
It was once thought that all chemo drugs would harm the fetus. But studies have shown that certain chemo drugs used during the second and third trimesters (the fourth through ninth months of pregnancy) do not raise the risk of birth defects, stillbirths, or health problems shortly after birth. But researchers still do not know whether these children will have any long-term effects.
When a pregnant woman with early breast cancer needs adjuvant chemo after surgery, it’s usually delayed until at least the second trimester. If a woman is already in her third trimester when the cancer is found, the chemo may be delayed until after birth. The birth may be induced (brought on) a few weeks early in these cases. Depending on the extent of the cancer, these same treatment plans may also be used for women whose disease is more advanced.
Chemo should not be given 3 to 4 weeks before delivery. This is because one side effect of chemo is that it lowers the mother’s blood counts. This could cause bleeding and increase the chances of infection during birth. Holding off on chemo for the last few weeks before delivery allows the mother’s blood counts to return to normal levels before childbirth.
Radiation therapy
Radiation therapy to the breast is often used after breast-conserving surgeries (lumpectomy or partial mastectomy) to reduce the risk of the cancer coming back. The high doses of radiation used for this can harm the fetus any time during pregnancy. It may cause miscarriage, birth defects, slow fetal growth, or a higher risk of childhood cancer so doctors do not recommend its use during pregnancy.
Pregnant women who choose lumpectomy or partial mastectomy can usually have surgery during the pregnancy and wait until after the baby is born to have radiation therapy. But this treatment approach has not been well-studied in pregnant women. And it is not known if the time delay might affect how well the radiation works.
Hormone therapy
Hormone therapy, such as treatment with tamoxifen, may be used as adjuvant treatment after surgery or as treatment for advanced cancer. Its use in pregnant women has not been well-studied, so its effects are not known. But there have been reports of miscarriage and fetal death, as well as head and face birth defects and genital defects in babies born to women who became pregnant while taking tamoxifen in early pregnancy.
More study in this area is needed. But at this time it is recommended that hormone therapy for breast cancer be delayed until after the woman has given birth.
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