OBJECTIVEThis study was conducted to analyze the Ki-67 expression before and after neoadjuvant chemotherapy and clinicopathological characteristics of different biological breast cancer phenotypes. The significance and prognostic predictive value of the changes of Ki-67 expression in different biological breast cancer phenotypes were analyzed.

METHODSA regression analysis was performed on 178 patients with invasive breast carcinoma who accepted neoadjuvant chemotherapy at Tianjin Medical University Cancer Institute and Hospital from August 2007 to August 2008. These patients were subtyped by hormone receptor status and HER-2 status. The Ki-67 index (percentage of Ki-67-positive cancer cell nuclei) was determined by immunohistochemistry. The prognostic value of Ki-67 index for disease-free survival (DFS) in different biological breast cancer phenotypes was analyzed using Kaplan-Meier survival and multivariable Cox regression.

RESULTSThe overall pathologic CR (pCR) rate, defined as no invasive residuals in the breast and axilla, was 15.2%. The highest pCR rate of 25.0% was observed in the TNBC patients, which was 14.3%, 10.3% and 18.2% in the luminal A, luminal B and HER2 overexpressing patients, respectively (P = 0.040). The changes of Ki-67 expression in pre-NAC and post-NAC patients showed a prognostic significance in luminal A and TNBC (P = 0.019 and P = 0.022, respectively) cases. Clinical stage, the efficacy of NAC, and changes of Ki-67 expression between pre- and post-NAC were independent prognostic factors in TNBC patients who did not achieve pCR.

CONCLUSIONSThe Ki-67 expression after neoadjuvant chemotherapy is an independent prognostic factor affecting the disease-free survival (DFS) in TNBC patients who have not achieved pCR.