Treating breast cancer during pregnancy

Surgery. Most pregnant women with breast cancer have a lumpectomy, also called breast-conserving surgery, or a modified radical mastectomy to remove the breast. Some of the lymph nodes under the arm may be removed so a pathologist can check them under a microscope for signs of cancer. If surgery is planned and the woman has already given birth, breastfeeding should be stopped to reduce blood flow in the breasts and make them smaller. Learn more about Breast Cancer Surgery, including reconstruction.

Chemotherapy. After the first 3 months of pregnancy, certain types of chemotherapy may be given before or after surgery. Chemotherapy given at this time does not usually harm the fetus but may cause early labor or low birth weight. Chemotherapy also should be avoided 3 to 4 weeks before delivery, because it can cause delivery complications for both the mother and baby. Women receiving chemotherapy should not breastfeed. Many chemotherapy drugs may be found in high levels in breast milk and could harm the nursing baby. Learn more about Chemotherapy for Breast Cancer.

Radiation therapy. Delaying radiation therapy until after the baby is born is usually the safest option. Women with late-stage breast cancer (stage III or stage IV) may consider external radiation therapy after a careful assessment of the risks and benefits. Talk with your doctor about the risks and benefits of radiation therapy as you discuss your treatment plan. Learn more about Radiation for Breast Cancer.

Other treatments. Hormone therapy, targeted therapy, and immunotherapy are usually not given to pregnant or nursing women because these treatments are harmful to a fetus or a nursing baby.