ERBB2 and breast cancer: HER2 agreement (HER2-null versus HER2-detectable) was moderate (Kappa = 0.50; 95%CI = 0.02–0.98) for primary breast cancer-lymph node metastasis pairs and fair for primary breast cancer-extracranial metastasis pairs (Kappa = 0.40; 95% CI = 0.0–0.73).