Impact of biomarker changes during neoadjuvant chemotherapy for clinical response in patients with residual breast cancers

Background Residual cancer burden or Ki67 expression levels in residual tumors reportedly provided significant prognostic information for a non-pathological complete response subset after neoadjuvant chemotherapy (NAC). However, the significance of Ki67 reduction for clinical response during chemotherapy in each subtype or menopausal status is yet to be determined.