Pregnancy and breast cancer.

Breast cancer and pregnancy are best considered as two discrete events which may occur either simultaneously or sequentially without any discernible biological interaction. There is no epidemiologic, clinical, or prognostic evidence that pregnancy, or its termination, will alter the natural history of breast cancer. Further, the existence of a pregnancy need not compromise effective breast cancer treatment, although the selection of modalities must consider fetal safety. Adjuvant radiotherapy, and thus breast conservation, is contraindicated unless it can be deferred until after completion of the pregnancy. Adjuvant chemotherapy is best delayed until after completion of the first trimester, and then, use of antimetabolites such as methotrexate and flourouracil should be avoided. Although the diagnosis of breast cancer during pregnancy may be only a biological coincidence, the emotional impact of this coincidence can be devastating on both patient and family. Informed medical care and compassionate support are both essential for women who simultaneously must confront the diametrically opposed implications and expectations of a life-giving and a life-threatening process.