Although cancer of the breast is one of the most common cancers diagnosed during pregnancy, it is a rare event, with 1 in 3000 to 3 in 10,000 deliveries being to women who were diagnosed with breast cancer while pregnant (1). The majority of data on this unique group of breast cancer patients are derived from retrospective case-control studies as well as case series and reports. Complicating the interpretation of the literature on breast cancer diagnosed during pregnancy is that this is often combined with pregnancy diagnosed in the year following delivery. Breast cancer diagnosed during pregnancy and the 12 months following delivery is referred to as pregnancy-associated breast cancer (PABC). It has been estimated that 0.2 to 3.8% of all breast cancers coincide with pregnancy or lactation (2). Given that increasing age is a risk factor for breast cancer, it has been postulated that the incidence of breast cancer during pregnancy may increase as more women delay childbearing (1).
A pregnant woman with breast cancer usually presents with a mass in her breast. However, the physiologic changes in a pregnant woman's breast, physician familiarity with PABC, as well as patient age, socioeconomic, cultural, and psychosocial factors are all thought to contribute to the delays in diagnosis that have been documented in older studies of pregnant and lactating women. These delays may be among the factors contributing to the later stage of diagnosis that has been documented in a number of case-control studies (1).
Although the majority of breast biopsies performed in pregnant women will demonstrate benign pathology, a breast mass that persists for 2 to 4 weeks should be further investigated. Any clinically suspicious breast mass should be biopsied for a definitive diagnosis whether a patient is pregnant or not. Even though a number of small studies have shown the accuracy of fine-needle aspiration (FNA) in the diagnosis of PABC, a core or excisional biopsy of the breast lesion is necessary to make a diagnosis of invasion (3).
Two large surgical series of pregnant patients who had general anesthesia for a variety of underlying medical problems failed to demonstrate an increase in the risk of congenital malformations as compared with pregnant women who did not undergo surgery (4,5). One of these series suggested that there may be an increased risk of spontaneous abortion with surgery in the first and second trimesters, especially after gynecologic procedures (4). The other surgical series found an increased incidence of very low and low-birth-weight infants among pregnant women, particularly in the first and second trimesters (5). The authors suggest that the underlying illness precipitating the surgery in pregnant women may have played a role in the incidence of very low and low-birth-weight infants.