Patterns of Relapse Related to High Expression of Ki-67 After Neoadjuvant Chemotherapy in Triple Negative Breast Cancer

Abstract

Introduction: Triple negative breast cancer (TNBC) has been classically considered a high-risk subtype. Early TNBC is usually managed with neoadjuvant chemotherapy (NAC). Residual disease after NAC is generally considered a surrogate marker for event free survival in these patients. The aim of this study was to explore the relationship between high Ki-67 expression in residual disease after NAC and disease relapse. Material and methods: This is a retrospective study of 121 patients diagnosed with TNBC, treated with neoadjuvant chemotherapy in our institution between 2008 and 2018. Clinical features, systemic and surgical therapy and pathological response were analyzed. Ki-67 expression was performed in the post-NAC surgical specimens when a pathological complete response (pCR) was not achieved. Results were correlated with number and type of relapse, and survival. Results: Eighty-one patients (67%) achieved a pCR with a median Ki-67 expression in the residual tumor of 22.5%. Thirteen patients (10.7%) relapsed and all of them belonged to the non-pCR group. In the non-relapse group, the median Ki-67 in the residual tumor was 10% compared to 40% found in the relapse group. (P=0.025). Median Ki-67 post NAC was 70% in those patients who developed a central nervous disease (CNS) relapse, 40% if was a nodal or bone recurrence and 28% if it was a visceral relapse. CNS recurrence was significantly associated with higher Ki-67 levels post NAC (P=0.010). Conclusions: Our results suggest that high expression levels of Ki-67 post-NAC could define different patterns of relapse in TNBC patients treated with NAC.