Ki-67 expression and its effect on response to neo-adjuvant chemotherapy in invasive breast cancer

Abstract

Objective: To investigate the response to neoadjuvant chemotherapy (NAC) among different molecular subtypes of breast cancers using molecular classification with Ki-67 (ER+ PR+ HER2+ Ki-67) or without Ki-67 (ER+ PR+ HER2). Methods: One hundred and twenty-seven cases of invasive breast cancer confirmed by core needle biopsy before NAC were collected from January 2007 to December 2009 and diagnosed at West China Hospital, Sichuan University. The cases were classified into different molecular subtypes using molecular classifications with or without Ki-67. Their clinical and pathological response to NAC was evaluated and compared. Results: The different subtypes using both molecular classifications showed significant difference in clinical response(with Ki-67: χ(2)=22.40, P<0.01; without Ki-67: χ(2)=9.202, P=0.027)but not pathological(P>0.05) response to NAC. By multivariate analysis, Ki-67 was predictive for a clinical complete response (P=0.041) and clinical overall response (P<0.01); also Ki-67 was the only clinicopathological factor predictive of pathological response(P=0.041). Conclusion: The molecular classification with Ki-67 is better to predict breast cancers responsiveness to NAC than the molecular classification without Ki-67.