Abstract ED3-1: Updates in the pathology of PABC

Abstract

Abstract Updates in the Pathology of Pregnancy Associated Breast Cancer (PABC) Pregnancy associated breast cancer is defined as a breast cancer diagnosed during gestation, lactation and within 1 to 5 years postpartum. While the development of malignancy during pregnancy is rare, the incidence is increasing; breast cancer is one of the most common cancers diagnosed during pregnancy and the postpartum period occurring in up to 1 in 3000 deliveries. Of interest, breast cancer is the leading cause of cancer death in US women age 15-29. Pregnancy has a dual effect on breast cancer development: on one hand cancer protective and on the other cancer promoting. While a number of hypotheses have been proposed over the years to explain these effects, the most likely hypothesis for the development of PABC is the involution hypothesis. This hypothesis proposes that the involution pathways activated during pregnancy and the immediate postpartum period are remodeling programs similar to wound healing and inflammation that may be associated with tumor development and progression. Although PABCs can be any subtype of breast carcinomas, they are usually invasive ductal carcinomas of high tumor grade and large tumor size with higher stage at presentation and higher rates of lymph node involvement. Most PABCs are hormone receptor negative tumors with high Ki-67 proliferation rates; most frequently, they are either triple negative or HER2-positive carcinomas. A number of studies have shown that PABCs have different genomic signatures than the non-PABC tumors with PABCs having an increased expression of immune response mediators. Better understanding of the molecular pathways of tumor initiation and progression and prompt diagnosis and state-of-art treatment protocols in PABC is expected to lead to better outcomes for these young breast cancer patients. Citation Format: Kalliopi Siziopikou. Updates in the pathology of PABC [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr ED3-1.