Hormone receptor expression in pregnancy-associated breast cancer: A systematic review of the literature

Introduction: Pregnancy-associated breast cancer (PABC) constitutes 7% of all breast cancers (BCs) and is defined as BC occurring anytime during gestation, lactation or within one year after delivery. As hormonal factors associated with pregnancy and lactation may play a complex role in such cases, hormone receptor status has been assessed in several studies with contradictory results.