Patients with germ line H/H polymorphism treated with the anti‐human epidermal growth factor receptor 2 (HER2) mAb trastuzumab for early HER2‐positive breast cancer were more likely to achieve pathological response while those with metastatic disease had better objective response rate and PFS.33, 34 The H/H polymorphism of FCGR2A was also associated with better response to anti‐TNF mAbs in patients with rheumatoid arthritis.36, 37 This evidence further supports a genetic role in determining cetuximab treatment outcomes. Here, FCGR2A is linked to breast cancer.