FGFR3 and in situ carcinoma: Approximately 70% of all BCs are non-invasive low grade (LG) BC (Ta/pT1/CIS), typically growing as superficial papillary protrusions, genetically associated to FGFR3 mutations and characterized by a high risk of recurrence together to a rare (10–15%) ability to progress to high grade (HG) and invade.