The goal of this clinical research study is to learn the results of multimodality (chemotherapy, surgery and radiation therapy) treatment of primary breast cancer that occurs at the same time as pregnancy. Researchers want to evaluate the outcome of labor and delivery as well as evaluate the long-term health outcomes of children exposed to chemotherapy while in their mother's womb.

Patients in this study will be evaluated by the Department of Breast Medical Oncology attending physician and the obstetrician. Patients who do not have an obstetrician will be referred to an obstetrician or Maternal-Fetal Medicine specialist for evaluation.

Counseling about primary breast cancer risks, staging evaluation, and breast cancer management will be provided by members of the Department of Breast Medical Oncology. Counseling about fetal health risks will be provided by the medical oncologists and the obstetrician or the Maternal-Fetal Medicine Specialist. Counseling about surgical risks will be provided by the Breast Surgical Service. Evaluation will include a medical history and physical exam. Doctors will be evaluating patients especially for the presence of metastatic disease. The date of the last menstrual period and estimated date of delivery will be recorded.

Patients in this study will have a chest radiograph with appropriate fetal shielding. Patients will have an ultrasound of the abdomen to evaluate the presence or absence of metastatic disease in the liver. If suspicious abnormalities are found, a MRI of the abdomen will be done. Scanning MRI of the thoracic spine will be performed to screen for bone metastases. Patients will have standard blood tests and a mammogram or ultrasound of the affected breast and lymph node bearing areas. Patients will have a tissue biopsy to confirm the status of the cancer. An ultrasound will also be performed to learn the age and development of the fetus.

Patients with operable primary breast cancer tumors will have surgical evaluation for surgical therapy with modified radical mastectomy or segmental mastectomy with lymph node dissection.

Patients with locally advanced breast cancers will receive systemic multi-agent chemotherapy in the presurgical setting.

Patients will have physical exams, mammograms, and ultrasounds repeated to evaluate tumor response to treatment. All patients who will receive chemotherapy will be offered systemic chemotherapy with 5-fluorouracil, doxorubicin, and cyclophosphamide (FAC).

Patients will be followed 6-12 months using the American Society of Clinical Oncology Guidelines and the Surveillance Committee Guidelines. All children will be followed until their adulthood. If the disease gets worse, patients will be treated off the study with individualized therapy. Premedication will be provided for all patients in order to decrease the risks of nausea and vomiting. When needed, adjustment in dosage of chemotherapy or modification in the way the medicines are given will be made in order to decrease any side effects.

This is an investigational study. The FDA has approved the study drugs. Their use together in this study is experimental. At least 100 patients will take part in this study. All will be enrolled at MD Anderson.

Inclusion Criteria:

· All patients with primary breast cancer occurring during pregnancy will be eligible for enrollment.

Exclusion Criteria:

• Patients presenting with systemic metastases at time of diagnosis.
• Patients unwilling or unable to give informed consent.
• Patients who have received radiation therapy while pregnant
• Patients who have received chemotherapy during the first trimester of pregnancy or chemotherapy other than FAC.