ERBB2 and breast carcinoma: A meta‐analysis of HER2+ breast cancer showed that the difference in survival between patients with pCR and those without was greater in hormone receptor‐negative breast cancer than in hormone receptor‐positive breast cancer (hormone receptor‐negative: HR, 0.29 [95%PI, 0.24–0.36], hormone receptor‐positive: HR, 0.52 [95%PI, 0.4–0.66]).29