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Breast Cancer and Pregnancy

When you’re pregnant, finding out that you also have breast cancer can be overwhelming. At the same time that you’re hoping to bring a new life into the world, you enter into a fight to protect your own life. You may be concerned that the treatment you need could harm your baby. Or you may worry that treatment won’t be as effective if you’re pregnant.

Pregnancy causes your breasts to swell and become tender as milk ducts grow and stretch to prepare for breastfeeding. Because of the swelling, it may be more difficult to detect small lumps. For this reason, women diagnosed with breast cancer during pregnancy tend to have more advanced cancers at diagnosis than other women with breast cancer. Still, most studies show that pregnant women respond to treatment as well as other women of the same age and with the same stage and type of breast cancer. It’s important for you to do everything you can to treat the breast cancer so you can mother your baby for many years to come.

According to the National Cancer Institute, breast cancer occurs about once in every 3,000 pregnancies. It’s good to know that most breast lumps found during pregnancy aren’t cancer. But you should still tell your doctor about any lump you find. DON’T WAIT until after you deliver your baby or finish breast feeding to have your doctor check the lump.

Treatment for Breast Cancer During Pregnancy

Because breast cancer during pregnancy is relatively rare, only small studies have been done on treating breast cancer during pregnancy. Still, it’s very important that pregnant women receive excellent breast cancer care. To ensure this happens, the National Comprehensive Cancer Network (NCCN), a group of 19 leading cancer institutions in the United States, developed guidelines for treating breast cancer during pregnancy. Hundreds of institutions around the world use these guidelines.

The treatment guidelines are different for each stage of pregnancy, so that mother and baby both receive the best possible care.

First trimester: If you’ve been pregnant for 3 months or less, the guidelines discuss the possibility of ending the pregnancy. The guidelines don’t say that you have to end your pregnancy because you’ve been diagnosed with breast cancer. But it is one of the choices available to you, and it’s important to consider all your options when making a decision.

In the first 3 months of pregnancy, if you decide to continue your pregnancy, the next step is mastectomy with axillary lymph node dissection. Mastectomy is recommended over lumpectomy and radiation at this stage of the pregnancy. That’s because radiation is not safe during pregnancy. (In women who aren’t pregnant, lumpectomy plus radiation may be as effective as mastectomy for those who are candidates.) After surgery, the guidelines suggest beginning chemotherapy in the second trimester. Chemotherapy should not be given during the first trimester. It is important to note that if radiation and hormonal therapy are necessary, they should wait until after the baby is born.

Second trimester: If breast cancer is found during the second trimester of pregnancy, the guidelines recommend either mastectomy or lumpectomy, with axillary lymph node dissection. Chemotherapy could be started before surgery. If you and your doctor opt for lumpectomy, then any necessary radiation therapy and hormonal therapy would be given after your child is born.

Third trimester: The guidelines recommend that if you are diagnosed with breast cancer in your third trimester you have either mastectomy or lumpectomy, with axillary lymph node dissection. Chemotherapy can be safely used if needed. Radiation and hormonal therapy, if necessary, would be given after the baby is born.

The guidelines note that most pregnant women diagnosed with breast cancer have been safely treated with combinations of the chemotherapy medicines Adriamycin (chemical name: doxorubicin), Cytoxan (chemical name: cyclophosphamide), and fluorouracil. The guidelines don’t mention the taxanes: Taxol (chemical name: paclitaxel), Abraxane (chemical name: albumin-bound paclitaxel), or Taxotere (chemical name: docetaxel). A few small studies suggest that the taxanes may be safe to use during the second and third trimesters of pregnancy.

The guidelines also don’t mention the targeted therapies: Herceptin (chemical name: trastuzumab), Tykerb (chemical name: lapatinib), and Avastin (chemical name: bevacizumab). Small studies have concluded that targeted therapies aren’t safe to use during pregnancy and should be avoided.


To diagnose breast cancer with certainty, in both pregnant and non-pregnant women, doctors need to remove a small portion of the suspicious breast lump. This procedure is called a biopsy. Such tissue can be removed by a needle (needle or core biopsy) or by surgical removal of the entire lump (excisional biopsy).

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 that will be biopsied. There is little risk to the baby. A biopsy also can be done under general anesthesia if need, with just a small risk to the baby.

Needle biopsies are safe in women who are breastfeeding. The risk of infection is higher with excisional biopsies because more surgery is involved, and breast milk can leak into the surgery area. If this does happen, the milk can be drained by fine needle aspiration.


Mammograms during pregnancy may be considered for women with signs or symptoms of a possible breast problem.

Small studies have found that it’s fairly safe to have a mammogram when you’re pregnant. Only a small amount of radiation is needed for a mammogram and the radiation is focused on the breast, so most of it doesn’t reach other parts of the body. For extra protection, a lead shield is placed on the belly to block any possible radiation scatter.

Regular screening mammography in women without any symptoms is not done during pregnancy.


According to the U.S. Food and Drug Administration, the safety of magnetic resonance imaging (MRI) during pregnancy hasn’t been established. Still, most small studies looking at MRI during pregnancy show it causes no problems. MRI is sometimes used to check breast lumps in pregnant women that look like they might be cancerous on a mammogram. Talk to your doctor about whether this type of test is safe for you and your baby.


Ultrasound is considered a safe tool for “seeing” inside the breasts of pregnant women. It is usually used before mammography to evaluate a palpable lump (a lump you can feel).

In both pregnant and non-pregnant women, ultrasound can accurately tell if a lump is a harmless cyst filled with fluid, or a solid mass that could be cancerous. But it is much less accurate at distinguishing between a solid lump that is breast cancer and a solid lump that is not.