“…Among tumor characteristics we considered: histological type, TNM classification and stage, eventual loco-regional extra-axillary lymph node involvement (internal mammary chain and subclavear), nuclear grading, Mib1/Ki-67 proliferation index, estrogen and progesteron receptors expression, Her2/neu status, and molecular subtypes. Moreover, we included other microscopical histological characteristics which are included in the more recent classification purposed by Veronesi and colleagues (Arnone et al 2010 ) as previously described (Cedolini et al 2014a , b , c ; Bertozzi et al 2013 ; Bernardi et al 2012a , b ), including multifocality/multicentricity, extensive intraductal component, perivascular invasion, peritumoral inflammation, lymph node extra-capsular invasion, and presence of bunched lymph nodes. Finally, we took into consideration also the therapeutic management: type of intervention on the breast (conservative breast surgery or mastectomy) and the axilla (sentinel lymph node biopsy or complete lymph node axillary dissection), eventual neoadjuvant or adjuvant therapies (chemotherapy, hormonal therapy, biological drugs, radiation therapy).…”