Genomic analysis of special types of invasive breast cancer

Breast cancer (BC) is a heterogeneous disease encompassing a wide array of categories of cell subpopulations, molecular aberrations and different clinical and pathological behaviors. The most challenging obstacle faced by clinicians is represented by a full understanding of such heterogene- ity and processes of resistance induced after the administration of anti- cancer drugs. For such reasons, BC is classified according to a number of several clinico-pathological and molecular factors. Over 20 histologic spe- cial types of BC are recognized by The World Health Organization (WHO) [1].Special types of BC account for approximately 20% of all newly di- agnosed cases. In spite of these mostly morphohistological classifications, treatment decisions are mostly guided by the size of the primary neoplasm at presentation, the involvement of locoregional lymph nodes, the status of few, actionable biomarkers such as estrogen and progesterone receptors and the amplification of the ERBB2/HER2 gene, as well as by the degree of differentiation and the proliferation index of cancer cells. The morphology of BC cells and their histological architecture, accounting for the identifica- tion of a special type, is almost not taken into account in clinical decisions by most guidelines [2]In this thesis, I focused on the molecular character- ization of special types of BC, with the purpose of identifying potential novel biomarkers of diagnosis, prognosis, and therapeutical prediction in such large, but in part neglected, class of tumors. Out of my research, I published two original scientific papers. The first one describes the ge- nomic landscape of four special types of BC: invasive lobular carcinoma (ILC), mucinous carcinoma (MUC), micropapillary carcinoma (MPC) and metaplastic carcinoma (META). The second one focuses on the molecular comparison between metaplastic carcinoma and uterine carcinoma, stem- ming from their similar histology and clinical behavior.