Development of tools to predict patients chemo-sensitivity and identification of corresponding biomarkers is an urgent challenge for BC patients lacking targeted therapies, such as TNBC, or for patients experiencing relapse after adjuvant chemotherapy or targeted therapies.

The refinement of 3D-cultivation techniques, experienced in the last decade, has allowed cultivation of patients-derived cancer cells in organotypic structures, named patient-derived organoids (PDO), which preserve histologic, genomic and transcriptomic features of primary tumors. PDO allow propagation, pharmacological treatment and genetic manipulation of patients-derived cancer cells in a close to physiology setting, thus representing a promising tool in the development of personalized therapies

PDO have been shown to efficiently recapitulate ex-vivo the in vivo response to hormonal treatment of BC patients. These observations point to PDO as potential valuable tools for a rapid, personalized prospective evaluation of patient-specific chemo-sensitivity. Moreover, PDO can represent a valuable ex-vivo platform for screening new treatments, or combination of current treatments, in a medium-to-high-throughput fashion. Thus, development of a stable collection of PDO representing the heterogeneity of BC subtypes, including the evolution of recurrent disease, represents an extremely useful resource for both prospective and retrospective studies aimed at understanding the molecular phenotype associated with chemoresistance.

Inclusion Criteria:

• women diagnosed with primary BC, eligible for surgical resection of the tumor according to national and international guidelines.

age between 18 and 70 years; newly diagnosed breast neoplasms, tumor size of at least 1.5 cm diameter.

Exclusion Criteria:

breast cancer diagnosed during pregnancy, neoadiuvant chemotherapy

Eligible population includes women diagnosed with primary BC, eligible for surgical resection of the tumor according to national and international guidelines. Each case will be discussed, before surgery, at the multidisciplinary tumor board for BC of the Fondazione Policlinico A. Gemelli, IRCCS.

All women will be required to sign written informed consent to enter the study. The study design has considered following inclusion criteria: age between 18 and 70 years; newly diagnosed breast neoplasms, tumor size of at least 1.5 cm diameter.