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Pregnant with Breast Cancer

Reviewed by: Elyce H. Cardonick, MD, FACOG

Updated August 30, 2013

It’s possible to be diagnosed with breast cancer and be pregnant at the same time. One in 3,000 pregnancies occurs in a woman diagnosed with breast cancer.

You might find out you have breast cancer during pregnancy or soon after. Or, perhaps you first learned of your pregnancy while being evaluated or treated for breast cancer.

When you receive a pregnancy-associated breast cancer diagnosis, your shock, worries, questions and fears are likely to be multiplied by health concerns for your fetus or, after delivery, for your infant. Take heart from knowing that studies suggest pregnant women who receive timely therapies, with precautions to protect the fetus:

  • Have similar survival outcomes as non-pregnant women of the same age treated for the same stage breast cancer  
  • Give birth to babies who show no long-term effects from treatment      

Breast Cancer During Pregnancy

Women under 40 represent 5 percent of new breast cancers, yet 7 to 15 percent may be pregnant at diagnosis.

Breast cancer risk increases with age, so those numbers are expected to go up as more women delay pregnancy. Risk rises slightly for those having a first pregnancy after age 30. Improved detection in young women may also lead to increased cases.

At one time, doctors and women thought pregnancy was too dangerous to continue during breast cancer treatment. It was believed a woman had to either terminate the pregnancy to start treatment right away, or delay therapy and risk her own survival until after the baby was born. Births were often medically induced (started early by a doctor) to speed time to treatment, causing complications for premature babies.

Now, research shows good results for women who have surgery or chemotherapy for breast cancer at appropriate times during pregnancy. Studies show that:

  • Ending a pregnancy by therapeutic abortion (done for medical reasons) does not improve survival in pregnant women diagnosed with breast cancer
  • Breast cancer treatment in pregnant women should follow the same therapy guidelines as for non-pregnant women, with some changes to protect the fetus. These include using older medicines, where we have much more information about their impact during pregnancy
  • Infants exposed to chemotherapy during pregnancy show normal development after birth

Many women now continue pregnancies during breast cancer treatment. For care, see oncologists and obstetricians or maternal-fetal specialists experienced in helping pregnant women with breast cancer.      

Your doctors may discuss terminating your pregnancy as one option, especially if you are diagnosed early in the first trimester (three months) of pregnancy, or have recurrent breast cancer that requires treatments not known to be safe in pregnant women.

  • What you decide to do is a personal choice, dependent upon your situation
  • Talk with an oncology social worker or counselor and others you may want to consult

Diagnosing Breast Cancer When Pregnant

Pregnancy can complicate breast cancer diagnosis. Breasts tend to be more dense and lumpy during pregnancy, so it may be difficult to feel a tumor until it grows larger, delaying diagnosis. Your dense breasts also make mammography less reliable. But if you do feel a mass, it’s important to get it checked out promptly.

To decide the best treatment, doctors must know the disease stage, lymph node involvement and whether hormone and HER2 (human epidermal growth factor) receptors are present, just as in a non-pregnant premenopausal woman.

Some diagnostic differences when you are pregnant:

  • MRI is preferred over CT scan due to lack of radiation exposure
    • If you need a CT or bone scan, an experienced radiologist can do them with some changes to regular techniques
      • If your doctor suspects bone metastasis, a non-contrast MRI can be used to check your spine
      • Mammogram or chest x-ray may be done, using a lead apron to shield the fetus
  • Ultrasound is effective and safe for the breast, axillary (underarm), abdomen and liver
  • Your biopsy sample may show cell changes due to pregnancy
    • Your pathologist must be told your tissue is from a pregnant breast
    • Breast cancers in pregnant women are often hormone receptor-negative. This is likely due to age and tumor types more common in young women

Treatment During Pregnancy

Before treatment begins, your obstetrician or a maternal-fetal expert should examine the fetus.  

Some therapies carry less risk to the fetus than others:

Discuss the timing of surgery and anesthesia risks for your fetus in advance with your doctors and anesthesiologist.

  • Mastectomy, removal of breast, may be used in all trimesters
    • avoids need for radiation in most cases
    • when needed, should be done using a similar time between diagnosis and surgery as a non-pregnant woman
  • Lumpectomy, removal of part of breast, is used later in pregnancy, so radiation can happen after delivery  
  • Axillary dissection removes lymph nodes to see if they contain cancer. Sentinel lymph node biopsy can be done safely during pregnancy with a radioactive tracer rather than blue dye.

In the first trimester, chemotherapy carries a high risk of harm to or miscarriage of your fetus. But some chemotherapy medicines can be used in second and third trimesters.

  • In general, the same medicines and dosing can be used as for non-pregnant women.This may include the combination of doxorubicin (Adriamycin), cyclophosphamide (Cytoxan) and 5-fluorouracil, and others
  • Methotrexate should not be used in the first trimester because studies show it causes miscarriage  
  • We are learning more about taxanes during pregnancy; studies have shown acceptable outcomes for the fetus. Your doctor may consider using taxanes if delaying your treatment until after delivery would be significantly longer than it would be if you weren’t pregnant, or your doctor feels the wait is too long
  •   A 2012 study of infants exposed to chemotherapy showed no effects on their general health, growth or neurocognitive abilities

You should not receive chemotherapy in the three to four weeks before delivery. It’s likely you will get regular ultrasounds during chemotherapy to check the growth of the fetus and the condition of amniotic fluid and placenta.

You cannot receive radiation therapy during pregnancy, unless it’s possible to expose your fetus to less than 5 to 10 rads. Often, this is not possible in breast cancer.

If you need radiation therapy after a lumpectomy, talk with your doctor about whether delaying radiation until after delivery would be too long a delay. In this case, you could consider mastectomy.

  • Hormonal and targeted (biologic) therapy should not be given during pregnancy or breastfeeding. Tamoxifen, a hormonal therapy, is known to cause birth defects. Targeted treatments such as trastuzumab (Herceptin) may cause low amniotic fluid, and infants born with reversible kidney issues. It may be possible to take these treatments once your baby is born. 

Outcomes After Delivery

When precautions are taken, infants born to mothers who received breast cancer treatment during pregnancy have no more problems than other babies. Studies show:

  • Breast cancer cells do not pass to infants
  • No more birth complications for pregnant women than for women without breast cancer
  • Low birth weight is related to premature delivery, not breast cancer treatment
  • No significant physical or developmental problems seen as children grow

If you keep your breast or breasts, it might be possible for you to breastfeed after delivery, with these cautions:

  • Chemotherapy before delivery significantly reduces milk production. Surgery may change your breast structure
  • If you have had a mastectomy, be reassured that an infant can receive enough nutrition from a single breast
  • Your pediatrician should follow your infant’s weight during breastfeeding

You should not breastfeed if you have chemotherapy or hormonal therapy after delivery. These medicines travel into breast milk. If you are planning surgery after delivery, you will need to stop breastfeeding to reduce breast size and risk of infection.

Despite often having breast cancer with more challenging biological features, pregnant women who are treated in a timely way, similar to how they would be treated were they not pregnant, experience no significant difference in recurrences, metastases or overall survival.

Getting Support During Pregnancy

If you are pregnant and diagnosed with breast cancer, it may help you to talk with others who are going through a similar experience, or have gone through it.

You also may be interested in:

  • Pregnancy & Cancer Registry, a confidential database which gathers information about women who are or were pregnant during cancer treatment. A related database collects information on pregnant women who have a history of cancer. Enroll confidentially at (877) 635-4499.

Resources for Pregnancy During Breast Cancer

Breast Cancer Treatment and Pregnancy, National Cancer Institute. English and Spanish versions.

Pregnancy and Breast Cancer, American Cancer Society.

This article was supported by Cooperative Agreement Number DP11-1111 from The Centers for Disease Control and Prevention. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the Centers for Disease Control and Prevention. 

Denver, CO  ·  September 13, 2014

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