Multimodal Cancer Therapy for Breast Cancer in the First Trimester of Pregnancy

OCCASIONALLY, because of clinical considerations, cytotoxic drug therapy is necessary during pregnancy, or unfortunately a patient conceives while under treatment. It is known that the human fetus is the most susceptible to teratogenic agents, such as x-radiation 1 and rubella virus, 2 during the first trimester, and it seems probable that this is also the case for cytotoxic chemotherapy. 3 It is important to assess the risks to which the fetus is subjected under these circumstances. The teratogenicity of antineoplastic agents has been proved in laboratory animals. Similar phenomena are seen in human fetal development when such drugs are administered during the first trimester of pregnancy. Aminopterin, which has been used in the past as an abortifacient, has been reported to cause profound abnormalities in a high percentage of fetuses. 2 Alkylating agents, especially cyclophosphamide, when administered during the first trimester, have been associated with major and minor abnormalities, including