Breast Cancer During Pregnancy

Reviewed by: HU Medical Review Board | Last reviewed: June 2023

Breast cancer rarely occurs during pregnancy. Statistics show it occurs in about 1 out of every 3,000 pregnancies. While cancer in any form is rare during pregnancy, breast cancer is the most common cancer diagnosed during pregnancy. When breast cancer is diagnosed during pregnancy, it can be complicated for both the mother and the baby.1,2

Breast cancer during pregnancy occurs most often in people between the ages of 32 and 38. However, it can occur in younger people. Genetic mutations may account for many of these breast cancers. About 33 percent of breast cancers in pregnant people in their 20s are due to a BRCA mutation. Roughly 22 percent of breast cancers in pregnant people in their 30s are due to a BRCA mutation.1,3

Signs of advanced breast cancer in pregnant people

Breast cancer can be difficult to detect in pregnant or breastfeeding people. This is because the breasts often become larger and/or lumpier, and potentially denser during pregnancy. These breast changes occur due to hormone changes in pregnancy. This can make it more challenging to find breast cancers when they are small.1

Common signs or symptoms of breast cancer during pregnancy include:1

  • A lump in the breast or underarm area
  • A change in breast size or shape
  • Dimples or puckering of the skin of the breast
  • The nipple turning inward
  • Fluid that is not breast milk, especially bloody fluid, leaking from the nipple
  • Scaly, red, or swollen breast or nipple

Delayed diagnosis

Many people who are diagnosed with breast cancer during pregnancy are in advanced stages of the disease when diagnosed. This is because signs of breast cancer may be difficult to detect due to the body’s changes during pregnancy.1,3

Diagnosing advanced breast cancer during pregnancy

To diagnose breast cancer during pregnancy, several tests may be used. These include:1,2

  • Clinical breast exam –An exam where the doctor feels the breast tissue and under the arm.
  • Mammogram – An X-ray taken of breast tissue while the breast is compressed between 2 plates. A lead shield can be placed over the abdomen to help protect the baby from any radiation.
  • Ultrasound – A screening that uses sound waves. It can be helpful in distinguishing between fluid-filled cysts or solid lumps.
  • Magnetic resonance imaging (MRI) – A scan that uses magnets and radio waves to create pictures of structures in the body.
  • Computed tomography (CT) scan – A scan that uses special X-ray equipment to make cross-sectional views of the inside of the body. A lead shield can be placed over the abdomen to help protect the baby from any radiation.
  • Biopsy – A procedure in which cells or the tumor are removed from the body to be examined under a microscope.

Treatment for advanced breast cancer during pregnancy

Treatment options for people with breast cancer during pregnancy are similar to other people with breast cancer. However, treatment approaches for breast cancer during pregnancy must consider the health of both the parent and the baby.

Some treatments, such as hormone therapy, immunotherapy, and targeted therapy, may be dangerous for the unborn child. This is why they are not given during pregnancy. Other treatments, including surgery, radiation, and chemotherapy, may be given during pregnancy. However, chemotherapy and radiation are not recommended during the first trimester (the first 3 months of pregnancy).1,2

In addition, people who are breastfeeding should not receive certain treatments. This is because they can pass into breast milk and could harm a baby that is nursing. People should not breastfeed while receiving treatment with chemotherapy drugs.1

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