In addition, Ignatov and colleagues performed a retrospective study of 205 patients with HER2‐positive breast cancer with residual disease—of which 167 received neoadjuvant single‐agent HER2‐targeted therapy and 19 received dual anti‐HER2 treatment—and reported an overall discordance rate of 42%.13 Here, ERBB2 is linked to breast carcinoma.