ERBB2 and metastatic neoplasm: Although rates of HER2 0 and HER2-low disease were similar between primary/residual and metastatic disease, discordance was observed in approximately a third of all matched samples (primary to metastatic disease Cohen’s kappa = 0.512, p < 0.001 and residual to metastatic disease Cohen’s kappa = 0.483, p < 0.001).