Breast cancer is the most common type of cancer in pregnant women. Frequently, patients are in their thirties; it has been estimated that the incidence of this disease will increase in the next few years because of women choosing to have children at a later age.
Diagnostic procedures normally used to determine the actual stage of cancer must be carefully evaluated to avoid excessive radiation during pregnancy. The timing of the studies is very important, even at very low radiation doses. Radiation exposure during the first trimester causes congenital malformations, particularly when the dose exceeds one hundred rads (radiation units). Radiological diagnostic procedures can be used at low dosage only when they are essential for treatment decisions and with proper abdominal shields.
Bone scans use lower radiation levels, and are the preferred diagnostic method for metastases. Ultrasound procedures are used for solid abdominal organs diagnoses and Magnetic Resonance Imaging (MRI) for brain metastases, although MRI safety has not been properly studied and documented so far for use in pregnancy. Although several low radiation procedures are used at present, there is always a risk of causing tumors in the child.
The pathology of breast cancers is similar for pregnant and non-pregnant women of the same age. Hormone receptor studies are usually negative in pregnant breast cancer patients, due probably to receptor binding by high serum estrogen levels. Other sensitive tests show that there is not much difference between pregnant and non-pregnant women.
Delayed diagnosis of breast cancer in pregnant women may affect their long-term survival. Abortion does not have a marked beneficial effect on the outcome; however, depending on the fetus’s age, termination of the pregnancy could be an option if the mother would benefit from chemotherapy and radiation therapies.
Early diagnosis is difficult in pregnant women because of the natural changes in the breasts; nodules and masses are very difficult to detect by physical exams and frequent self-examinations. If abnormalities are found, then ultrasound and mammography—with proper shielding—are indicated, although up to one in four mammograms may be negative. When masses or other changes are found, then needle biopsies are of great diagnostic value.
Medical suppression of lactation does not change the course of the disease, but it must be done when surgery is considered and also when chemotherapy is determined to be beneficial to the mother. Breast-feeding should not be done while receiving anti-cancer medications.
It has not been demonstrated that pregnancy would compromise the survival of women who had breast cancer. However, patients should wait for at least two years after being treated before getting pregnant; this period would allow for the proper diagnosis in cases of early recurrence.
At this time, there is no much information regarding the outcome of pregnancies after high-dose chemotherapy and bone marrow transplants, with or without total body irradiation.
Surgery is the treatment of choice for breast cancer in pregnant women. Since radiation in therapeutic doses may expose the fetus to excessive radiation, modified radical mastectomy is the most used technique. Postpartum radiation therapy has been used for breast preservation.
If chemotherapy is necessary, it should not be given during the first trimester; the risks of malformation decline in the second and third trimesters, although it may induce premature labor and low weight babies. Radiation therapy should not be used until after delivery, because it may be harmful to the fetus at any stage of development.
If chemotherapy, radiotherapy, and other standard treatments are not used because of pregnancy, survival is affected to the point where only one out of ten mothers would be alive at five years, if their disease progressed to the point of generalized metastases. Abortion should be considered in order to start radiation, anticancer medications, etc.; abortion alone does not improve the long-term outcome. Please visit our Web site for more information.
By Colleen S. Mills, MD
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