ERBB2 and breast carcinoma: Conversely, T1c HER2+/HoR‐ breast cancers revealed worse prognosis than T1a/T1b HER2+/HoR‐ and T1c HER2‐/HoR+tumors (BCSS HR 3.847, P < 0.001; OS HR 2.055, P < 0.001).