Factors Affecting Pathologic Complete Remission in Patients with Hormone Receptor-Positive and Human Epidermal Growth Factor Receptor 2-Negative Breast Cancer Receiving Neoadjuvant Chemotherapy.

Abstract

Pathological complete response (pCR) after neoadjuvant chemotherapy (NAC) is associated with improvement in survival outcomes. This study evaluated the pCR in patients with hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancer after NAC. We evaluated 417 patients who were diagnosed with invasive breast cancer and treated with NAC followed by curative surgery between January 2007 and December 2020 and analyzed the pCR for HR-positive and HER2-negative breast cancer. The median age at the time of surgery was 45.4 years, and 9.1% of patients (38 of 417) with HR-positive/HER2-negative status had pCR. Among patients with HR-positive/HER2-negative breast cancer, patients with single HR-positivity had a 20.2% pCR rate, and patients with double HR-positivity had a 4.4% pCR rate. Patients with a high Ki-67 index exhibited a higher pCR rate than those with a lower Ki-67 index (14.5% vs. 3.2%). Patients with single HR-positive and high Ki-67 values exhibited a significantly higher pCR rate than those with double HR-positive and low Ki-67 values (27.8% vs. 2.1%; p < 0.001). NAC could improve prognosis in patients with HR-positive/HER2-negative breast cancer with a single HR-positive and high Ki-67 values.