Predictive Significance of p53, Ki-67, and Bcl-2 Expression for Pathologic Complete Response after Neoadjuvant Chemotherapy for Triple-Negative Breast Cancer

PURPOSE: Patients with triple-negative breast cancer (TNBC) with pathologic complete response (pCR) to neoadjuvant chemotherapy (NAC) have superior survival outcomes compared to those with residual disease after NAC. This study investigated the value of three biomarkers, p53, Ki-67, and Bcl-2 for predicting pCR in NAC-treated patients with TNBC. METHODS: Between 2003 and 2012, 198 patients with pathologically confirmed primary TNBC were treated with two different taxane-based chemotherapeutic regimens prior to surgery. Before NAC, expression of p53 (cutoff 25%), Ki-67 (cutoff 10%), and Bcl-2 (cutoff 10%) was assessed immunohistochemically in core biopsy specimens. The incidence of pCR was correlated with the expression of these biomarkers. RESULTS: Overall, pCR occurred in 37 of the 198 patients (18.7%). A significant association was observed between the pCR rate and overexpression of the p53 and Ki-67 biomarkers. Multivariate analysis showed that only p53 expression was independently associated with pCR to NAC (odds ratio, 3.961; p=0.003). The sensitivity, specificity, positive predictive value, and negative predictive value of p53 expression for predicting pCR were 77.8%, 50.3%, 26.2%, and 90.9%, respectively. The pCR rate was the lowest (5.2%) in patients with low expression of both p53 and Ki-67, and it was the highest (25.8%) when both biomarkers showed high expression. CONCLUSION: Expression of p53 was significantly associated with pCR after NAC in patients with TNBC, suggesting that this biomarker might be particularly valuable in identifying TNBC patients prone to have residual disease after NAC.