Further supporting evidence in the same trial is that the IDFS of patients with heterogenous HER2 expression, mostly evident in HER2 IHC 2+ cases, was too close to homogenous expression, mostly in HER2 IHC 3+ in the T-DM1 arm (89 and 88%, respectively) compared to the trastuzumab arm where less benefit was seen in tumours with heterogenous HER2 expression [54]. Here, ERBB2 is linked to neoplasm.