Towards personalized care in pregnancy-associated breast cancer: the importance of the clinicopathologic profile

Within the last decade, there has been considerable progress in managing breast cancer that develops during pregnancy. The increased knowledge on the safety of available treatment options for pregnant women, and perhaps even more importantly for their offspring, has led to more adequate breast cancer treatment during pregnancy. In contrast, little progress has been made in unravelling the complex biology and pathophysiology of pregnancy-associated breast cancer (PABC). The molecular nature of PABC currently remains an unknown field, while literature provides considerable controversy regarding the influence of pregnancy on breast carcinogenesis and prognosis. This indicates the need for clear definitions, more insights into clinicopathologic profiles of young women with breast cancer during pregnancy, during lactation, and outside of pregnancy, as well as exploring the role of potential subgroups within PABC.
Research within this thesis was conducted to create a comprehensive overview of the clinicopathologic characteristics and outcomes of PABC patients, subdivided according to gestational trimesters and (for postpartum patients) lactational status at diagnosis, as compared to (age-)matched non-pregnant young breast cancer patients. In addition, molecular differences between PABC subgroups were identified. These molecular differences may serve as a starting point for additional biomarker research into individualized early-stage diagnosis and treatment. Altogether, this detailed PABC fingerprint may serve as a fundament for further in-depth research into PABC carcinogenesis, and thereby, potentially provide a way forward to well-defined personalized care of this unique breast cancer subtype.