LAUSR

Loss of HER2 “positivity” can occur in patients with residual disease after neoadjuvant treatment, but the incidence of HER2‐positivity loss after neoadjuvant dual HER2‐targeted treatment plus chemotherapy, the current standard‐of‐care for most early stage HER2‐positive breast cancers, is not well described. Previous studies that report the HER2 discordance rate after neoadjuvant treatment also do not include the novel HER2‐low category. In this retrospective study, we determine the incidence and prognostic impact of HER2‐positivity loss, including the evolution to HER2‐low disease, after neoadjuvant dual HER2‐targeted therapy with chemotherapy.