Carcinoma of the Breast in Pregnancy and Lactation

Abstract Epidemiologic studies demonstrate that, overall, pregnancy is associated with a reduced lifetime risk of developing breast cancer. Yet this protective effect is not constant or immediate. Although uncommon, the development of breast cancer during the gestational or lactational period has traditionally been attributed a poor prognosis. With a tendency to delayed childbearing, an increase in the incidence of pregnancy-associated breast cancer is possible. This review outlines a tailored approach to the evaluation, diagnosis, and management of breast cancer during pregnancy. The majority of breast masses during pregnancy are benign, but the index of suspicion for cancer must be high for women who present with a breast mass during this period. Ultrasound and core biopsy are the fundamental diagnostic means. Many of the management strategies mirror those used in the treatment of breast cancer outside of pregnancy, with some important differences. Surgery and systemic chemotherapy, either in the neoadjuvant or adjuvant settings, are feasible options for most women during pregnancy. Chemotherapy is contraindicated in the first trimester of pregnancy, but after this, dose-dense regimens, including anthracyclines and taxanes, have been used with limited risk for both the mother and the fetus. Where patient and tumor factors allow, breast-conserving surgery followed by postpartum radiotherapy is appropriate. For axillary staging, the radiocolloids used for sentinel node mapping are safe to use given the locoregional administration. Recent advances have improved oncologic outcomes in patients with breast cancer, but not all of these have been adapted for pregnant patients. With serious adverse events on both the pregnancy and fetus, prolonged exposure to trastuzumab should be avoided. Further research, potentially through case registries with rigorous follow-up, is required to evaluate outcomes with pregnancy-associated breast cancer.