Patients
Institutional databases were reviewed to identify stage I-III breast cancer patients who received NAC, BCS at Sun Yat-sen Memorial Hospital, Sun Yat-sen University from 2011 to 2016. This study was approved by the Institutional Review Board (IRB) (SYSECKY-KS-2020-116)at Sun Yat-sen Memorial Hospital. All patients were proven to have invasive breast carcinoma by core needle biopsy. Clinicopathologic data including demographics, clinical oncologic features (tumor size, nodal stage) and tumor complete receptor information (ER, PgR, and HER2) was collected. The clinical and pathologic stages were defined according to the 8th edition of the American Joint Committee on Cancer guidelines. Clinical stage was determined by ultrasound of the breast and lymph nodes. Lymph nodes with an abnormal appearance on ultrasound were routinely evaluated with a core-needle biopsy. A cutoff of 1% was used to determine the HR status on the core biopsy specimens. Tumors were defined as HER2 positive if they were 3+ by immunohistochemistry or demonstrated gene amplification by fluorescence in situ hybridization13. Overall pathologic complete response (pCR) was defined as no residual invasive cancer in the breast or axillary lymph nodes.