Since the conception of the definition of PABC, more data on the cellular and molecular differences between PrBC and PPBC (including their respective tissue microenvironments figure, B) have become available. In clinical practice, this difference is obvious: the treatment of PrBC is individualised according to gestational age and taking foetal safety into consideration, whereas treatment decisions for PPBC do not need to account for these concerns. ...there is a need for a better understanding of the importance of parity status as an independent prognostic factor for worse outcomes in premenopausal breast cancer. Only a separate investigation of both entities will improve our understanding of the biology of breast cancer during pregnancy, lactation, involution, and thereafter, and help to decipher the pathways underlying differences in tumour biology. ...we recommend that the term PABC is no longer used, allowing investigators to focus specifically on breast cancer during pregnancy (PrBC) or during the postpartum period (PPBC), which could ultimately lead to optimised therapeutic modalities, particularly for PPBC with a poor prognosis.