In contrast, in the NSABP B-47/NRG Oncology clinical trial testing whether addition of trastuzumab to adjuvant chemotherapy would improve invasive disease-free survival (IDFS) in patients with ERBB2-non-amplified, HER2 IHC 1+ or 2+ high-risk invasive breast cancer, trastuzumab did not prolong IDFS regardless of HER2 expression level (26). Here, ERBB2 is linked to invasive breast carcinoma.