Prognostic value of receptor conversion after neoadjuvant chemotherapy in breast cancer patients: a prospective observational study

The hormone receptor (HR) status and human epidermal growth hormone receptor 2 (HER2) status of patients with breast cancer may change following neoadjuvant chemotherapy (NCT). This prospective observational study aimed to evaluate the prognostic impact of receptor conversion in breast cancer patients treated with NCT.Of the 423 consecutive patients who had residual disease in the breast after NCT, 55 (13.0%) changed from HR (+) to HR (-), 23 (5.4%) changed from HR (-) to HR (+), 27 (6.4%) changed from HER2 (+) to HER2 (-), and 13 (3.1%) changed from HER2 (-) to HER2 (+). A total of 54 (12.8%) changed to the triple-negative (TN) tumor phenotype. The loss of HR positivity was an independent prognostic factor for worse disease-free survival (DFS) and worse overall survival (OS) in multivariate survival analysis. Furthermore, the switch to the TN phenotype after NCT was another independent prognostic factor for worse survival for both DFS and OS. In conclusion, patients with breast cancer may experience changes in HR status, HER2 status and tumor phenotype after NCT. The loss of HR positivity and the switch to the TN phenotype after NCT were associated with a worse patient outcome.