Breast cancer is diagnosed in about 1 pregnant woman out of 3,000. In general, treatment recommendations depend upon how long the woman has been pregnant.
Radiation therapy during pregnancy is known to increase the risk of birth defects, so it is not recommended for pregnant women with breast cancer. For this reason, breast-conserving therapy (lumpectomy and radiation therapy) is only an option if radiation can wait until it is safe to deliver the baby. But breast biopsy procedures and even mastectomy and lymph node removal are safe for the mother and fetus.
For a long time it was assumed that chemotherapy was dangerous to the fetus. But several studies have found that using certain chemotherapy drugs during the second and third trimesters (the fourth to ninth months) does not increase the risk of birth defects. Because of concern about the potential damage to the fetus, the safety of chemotherapy during the first trimester (the first 3 months) of pregnancy has not been studied.
Hormone therapy may affect the fetus and should not be started until after the patient has given birth.
Many chemotherapy and hormone therapy drugs can enter breast milk and could be passed on to the baby, so breast-feeding is not usually recommended during chemotherapy or hormone therapy.
For more information, see our document, Pregnancy and Breast Cancer.
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