The use of chemotherapeutic agents during pregnancy

Cancer complicating pregnancy is uncommon, with an incidence of approximately 1 per 1000 pregnancies. The American College of Obstetricians and Gynecologists estimates that approximately 3500 cases of cancer occur in pregnant women annually in the United States.(25) The most common malignancies encountered during pregnancy, in descending order, are cervical, breast, melanoma, ovarian, thyroid, leukemia, lymphoma, and colorectal. Pregnancy per se does not increase the risk of malignancy. The incidence of specific malignancies during pregnancy parallels that of nongravid women of comparable age. The incidence of cancer complicating pregnancy may increase as child-bearing is delayed to later in life. For women with breast cancer, ovarian cancer, leukemia, and lymphomas, chemotherapy may have a major role in treatment.(6) Chemotherapy may be given for a variety of indications (Table 1). Appropriate use of chemotherapeutic agents requires knowledge of the mechanism of action, effect on the cell cycle phase, and toxicity. Unfortunately, there are no large prospective series that address chemotherapy use during pregnancy and, thus, most physicians are forced to formulate treatment regimens based on small retrospective studies or case reports. The ultimate decision to delay or initiate chemotherapy during pregnancy is difficult and must take into account the emotional, religious, social, and moral needs of the mother and family. The primary concern of pregnant women with cancer is ''living to see my child grow up.''(3) However, the necessity of using therapeutic maternal doses of chemotherapeutic agents must be balanced against the risks to the fetus. The effects of chemotherapy on the developing fetus must be balanced in turn against the effects of the maternal illness on the fetus. The potential exists for a conflict. Because the incidence of carcinoma requiring chemotherapy during pregnancy is small, few individuals or institutions will attain sufficient experience with this clinical scenario. This review offers clinicians useful information upon which to advise their patients. This is particularly important because information in the older literature may be of limited relevance as lower doses of single agent chemotherapy were commonly used.(19)