Impact of hormone receptor and HER2 conversions on survival after neoadjuvant chemotherapy in breast cancer patients

Background: This study assessed the frequency of changes in some key receptor status of tumors after neoadjuvant chemotherapy（NAC） in patients with invasive breast cancer and the prognostic impact of these changes.Methods: This study included 300 patients diagnosed with invasive breast cancer who were treated with both NAC and surgery between 2012 and 2021. The hormone receptor（HR） and human epidermal growth factor receptor 2（HER2） levels were measured before and after NAC. The prognostic impact of receptor conversion was also evaluated in patients receiving NAC, by using the Kaplan-Meier method and Cox proportional hazards models as statistical methods.Results: The conversion rate of estrogen receptor–positive（ER+） to ER-negative（ER-） was similar to that of ER- to ER+（9.2% and10.9%, respectively）. The proportion of HR- to HR+ was remarkably higher than that of HR+ to HR-（14.8% vs 9.2%, respectively）. The change from HER2+ to HER2- was significantly more frequently than that from HER2- to HER2+（20.3% vs 6%, respectively）. Patients with ER and HR status changes from（-） to（+） after NAC had significantly worse recurrence-free survival（RFS） and overall survival（OS） than those in the other 3 groups（ER- to ER+: RFS: p = 0.002, OS: p < 0.001; HR- to HR+: RFS: p = 0.003, OS: p < 0.001）. The 4 HER2 conversion subgroups were not significantly associated with RFS or OS.Conclusions: This study demonstrated a discordance in HR status after NAC and identified predictors of conversion. Patients whose HR status switched to positive after NAC had the worst 3-year RFS and OS rates.