Breast cancer during pregnancy is relatively rare. About 1 in every 3,000 people who are pregnant develop breast cancer, but it is the most common type of cancer found during pregnancy.

Those statistics come from the National Cancer Institute.

Pregnant people will experience changes in their breasts such as swelling and tenderness, which may result in lumps. While many lumps that develop during pregnancy are not cancerous, a person should still have any lumps they find checked by a health professional.

Many pregnant people who receive a diagnosis of breast cancer respond to treatment just as well as non-pregnant people of the same age with the same stage of cancer.

However, a pregnant person may face complications in treating their cancer, as there may be conflicts between the best-known treatment for the parent and the well-being of the baby.

This article will discuss the safety of breast cancer treatment while pregnant, including surgery and chemotherapy, and will also discuss treatment in relation to breastfeeding.

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People with breast cancer who are pregnant can undergo certain treatments safely, although some carry a higher risk to an unborn baby.

The National Comprehensive Cancer Network (NCCN) offers guidelines on safe treatment for the parent and baby according to how far along the pregnancy is. Access to the guidelines is free, but requires registering an account.

First trimester

Experts recommend a mastectomy with lymph node biopsy, according to the NCCN guidelines. A mastectomy is the surgical removal of the breast tissue from a breast. Testing the lymph nodes in the armpit can indicate whether or not the cancer has spread from the breast area.

Experts recommend a mastectomy, rather than a lumpectomy with radiation, because radiation is not safe for the fetus. A lumpectomy is the surgical removal of cancerous or abnormal tissue from the breast.

Chemotherapy is not safe for the fetus during the first trimester of pregnancy.

If a patient decides to pursue breast cancer treatment that would endanger a fetus, such as that used to treat an aggressive form of cancer, they may choose to terminate their pregnancy and concentrate fully on treatment. However, research suggests that ending a pregnancy does not appear to affect the mother’s chances of survival.

Second trimester

If doctors diagnose breast cancer during a person’s second trimester of pregnancy, the NCCN guidelines recommend either a mastectomy or lumpectomy, with the biopsy of a lymph node from the armpit.

Doctors may also start chemotherapy before surgery. If the doctor and patient agree on a lumpectomy, the patient should receive radiation therapy and possibly hormonal therapy at the end of the pregnancy.

Third trimester

The NCCN guidelines recommend that if a doctor diagnoses a person with breast cancer during the third trimester of their pregnancy, they should undergo either a mastectomy or lumpectomy, with lymph node biopsy.

A person can safely receive chemotherapy during this trimester, but they should only receive radiation or hormonal therapy at the end of the pregnancy.

According to the guidelines, it is safe for a person to have surgery for breast cancer while pregnant. Chemotherapy is generally safe for the parent and baby during the second or third trimester of pregnancy.

A doctor can often perform breast cancer surgery on a patient safely during any stage of pregnancy. A doctor and patient will decide together whether the patient will receive a mastectomy or lumpectomy.


Doctors most often use a mastectomy for people with breast cancer, as a lumpectomy usually requires radiation therapy following surgery.

Doctors are more likely to recommend a mastectomy during the earlier stages of pregnancy. This is because the patient would have to wait until after the pregnancy to begin radiation therapy following a lumpectomy, which would increase the risk of cancer returning.


Doctors may suggest lumpectomy at the later stages of a patient’s pregnancy, as there will not be as long a delay before the patient can receive radiation therapy.

Anesthesia and safety

Doctors can generally safely perform surgery for breast cancer on pregnant people, but there are certain times during pregnancy where anesthesia may carry a higher risk for the baby.

A surgeon, anesthesiologist, and obstetrician will decide the best stage of the pregnancy to perform the surgery. If a surgeon performs the surgery in the later stages of the pregnancy, an obstetrician may be present in case any complications occur with the baby.

Doctors may prescribe chemotherapy either by itself for advanced cancers, or following surgery for some earlier stages of breast cancer.

Doctors will not give chemotherapy to people with breast cancer during the first 3 months of their pregnancy, as much of the baby’s development takes place during this time. Researchers have not studied the safety of chemotherapy during this time in a pregnancy.

Although people previously believed chemotherapy carried a risk to unborn babies, studies have found that using certain chemotherapy drugs during months 4–9 of a pregnancy does not increase the risk of health problems shortly after birth.

Researchers still do not know if chemotherapy has any long-term effects on children whose parents received it during pregnancy.

If a person requires chemotherapy after breast surgery, doctors will usually delay it until a patient’s second trimester. If the breast cancer is diagnosed while the patient is in their third trimester, chemotherapy may be delayed until after the end of pregnancy. Doctors may induce early labor in some cases in order to begin chemotherapy sooner.

Doctors do not generally recommend chemotherapy after 35 weeks of pregnancy or within 3 weeks of delivery, as it can lower the parent’s blood cell counts.

Certain breast cancer treatments can harm an unborn baby and are not safe during pregnancy. Doctors will typically avoid these treatments until after a pregnancy has ended:

  • Radiation therapy: Doctors usually give radiation therapy to a patient following a lumpectomy to reduce the risk of cancer returning. As doctors use high doses of radiation for this therapy, a baby would be at risk of slow fetal growth, birth defects, and childhood cancer. There is also a higher risk of miscarriage.
  • Hormone therapy: Doctors use drugs such as tamoxifen to remove hormones or stop their actions in patients with hormone receptor-positive breast cancer. Doctors often prescribe hormone therapy following breast surgery.
  • Targeted therapy: Doctors may use drugs to target the growth-promoting protein HER2 in breasts to treat HER2-positive breast cancer.

Most experts recommend that a person with breast cancer should avoid breastfeeding.

Stopping breastfeeding will help reduce blood flow to the breasts and make them smaller, which is beneficial for breast surgery. Stopping also will help reduce the risk of infection in the breast and can help prevent milk collecting in surgery or biopsy areas.

It is important that people continue breast cancer screening and speak to a healthcare professional about any lumps in their breasts during pregnancy.

During pregnancy, it can be more difficult for people to notice signs and symptoms of breast cancer. This is because the breasts swell and become tender as milk ducts grow and stretch to prepare for breastfeeding.

People who are pregnant should not conclude small lumps are pregnancy-related and ignore them, as they could be the beginnings of cancer.

Some people may also delay breast cancer screenings and mammograms until after their pregnancy. When people do have screenings, pregnancy can cause denser breast tissue, which may make it more difficult to see signs of early cancer.

Learn more about the early signs of breast cancer here.

Some experts recommend only performing certain procedures to check for the spread of cancer later in pregnancy or after birth.

Doctors can safely remove lymph nodes from under the arm and check them during surgery to determine if cancer has spread.

However, doctors may opt against sentinel lymph node biopsy (SLNB), which uses slightly radioactive tracers and a blue dye to find the nodes most likely to contain cancer cells.

Doctors remove fewer nodes when performing an SLNB, but there are concerns about the effects the dye might have on an unborn baby. As a result, experts recommend that doctors only use SLNB later in pregnancy, and not use blue dye during the procedure.

While some methods of breast cancer diagnosis are safe to use during pregnancy, certain methods may put the baby at risk.

  • Mammograms can detect most breast cancers, and are generally safe during pregnancy. Mammograms use minimal radiation, and focus radiation on the breast, which does not endanger the baby. Doctors or assistants may place a lead shield over the belly to offer extra protection.
  • Ultrasound exams do not use radiation. It is safe for doctors or assistants to perform ultrasound exams on pregnant people.
  • MRI scans during pregnancy may not be safe. The dye that doctors use during many MRIs may cross the placenta. Tests have linked this dye with fetal abnormalities in laboratory animals, which is why doctors do not recommend MRI scans during pregnancy. Doctors may use an MRI without dye if necessary, however.
  • Breast biopsies are typically outpatient procedures and involve the use of a hollow needle to remove small pieces of breast tissue. The doctor uses medicine to numb the area. Doctors consider biopsies to be generally safe for a fetus.

Does pregnancy increase the risk of breast cancer?

Some pregnancy-related factors may increase breast cancer risk. The older a female is during her first full-term pregnancy, the higher their breast cancer risk. After pregnancy, a female has a higher risk of breast cancer that decreases after around 10 years. Females who took diethylstilbestrol (DES), a synthetic form of estrogen, during pregnancy, may have a higher risk of developing breast cancer.

Which type of breast cancer is most common in pregnancy?

Ductal infiltrating adenocarcinoma is the most common type of breast cancer during pregnancy and outside of pregnancy. It begins in the breast’s milk ducts and can spread to surrounding tissue.

Read more about ductal carcinoma.

What is the survival rate for breast cancer during pregnancy?

The 5-year survival rate for people with stage 3 or 4 breast cancer is 10%. This means that 10% of people receiving this diagnosis will live for 5 years or more.

A small Danish study in 2022 compared survival rates of women diagnosed with breast cancer during pregnancy with non-pregnant women with breast cancer. The pregnant group had a higher overall mortality for the first 2 years following diagnosis. Survival in both groups was similar after 2 years.

Surgery for breast cancer is generally safe for the parent and baby during pregnancy, although doctors are more likely to advise mastectomy over lumpectomy during early stages of pregnancy. This is because radiation often follows lumpectomy, which could harm the fetus.

Certain breast cancer treatments are not safe for the baby during pregnancy, including forms of hormonal, radiation, and targeted therapy.

It is generally safe for doctors to give pregnant people chemotherapy during the second and third trimesters of pregnancy.

Doctors recommend that people do not breastfeed if they have breast cancer, as this can increase the size of breasts and cause milk to gather in surgery or biopsy sites.

It may be more difficult for patients and doctors to identify signs and symptoms of breast cancer during pregnancy, such as lumps and swelling.

Some methods of diagnosis and checking for swelling may not be safe for doctors to use on pregnant people. Mammograms and ultrasound exams are safe during pregnancy.