title: Ki-67 as a predictor of response to neoadjuvant chemotherapy in breast cancer patients.
abstract: OBJECTIVE
  The objectives of this study were to assess the potential value of Ki-67 in predicting response to neoadjuvant chemotherapy in breast cancer patients and to suggest a reasonable cutoff value for classifying Ki-67 expression.
  
  
  METHODS
  This study included 74 breast cancer patients who underwent surgery after anthracycline-based neoadjuvant chemotherapy between 2007 and 2012. We analyzed the clinical and immunohistochemical characteristics using core biopsy specimens obtained before neoadjuvant chemotherapy to determine their correlations with the response to chemotherapy.
  
  
  RESULTS
  A clinical complete response was observed in 6 patients (8.1%); a clinical partial response, in 44 patients (59.5%); and clinical stable disease, in 24 patients (32.4%). A pathologic complete response (pCR) was observed in 10 patients (13.5%). In univariate analysis, estrogen receptor (ER) negativity (p=0.031), human epidermal growth factor receptor 2 (HER2) positivity (p=0.040), and high Ki-67 expression (p=0.036) were predictive factors for a pCR. In multivariate analysis, Ki-67 was the only independent predictor of a pCR (p=0.049). The analysis of Ki-67 values revealed that 25% was a reasonable cutoff value for predicting the response to chemotherapy. In subgroup analysis, a higher Ki-67 value (≥25%) was a significant predictive factor for the response to neoadjuvant chemotherapy, especially in ER-negative and HER2-positive breast cancer patients.
  
  
  CONCLUSIONS
  Ki-67 expression in breast cancer tissue may be an effective factor for predicting the response to neoadjuvant chemotherapy. We suggest that a 25% level of Ki-67 expression is a reasonable cutoff value for predicting a response to chemotherapy. Moreover, Ki-67 is a useful predictive factor for pCR, especially in patients with ER-negative and HER2-positive breast cancer.
authors.affiliation: Department of Surgery, Gachon University Gil Hospital, Incheon, Korea.
authors.forename: Kwan Il
authors.initials: KI
authors.lastname: Kim
authors.affiliation: Department of Surgery, Gachon University Gil Hospital, Incheon, Korea.
authors.forename: Kyung Hee
authors.initials: KH
authors.lastname: Lee
authors.affiliation: Department of Surgery, Gachon University Gil Hospital, Incheon, Korea.
authors.forename: Tae Ryung
authors.initials: TR
authors.lastname: Kim
authors.affiliation: Department of Surgery, Gachon University Gil Hospital, Incheon, Korea.
authors.forename: Yong Soon
authors.initials: YS
authors.lastname: Chun
authors.affiliation: Department of Surgery, Gachon University Gil Hospital, Incheon, Korea.
authors.forename: Tae Hoon
authors.initials: TH
authors.lastname: Lee
authors.affiliation: Department of Surgery, Gachon University Gil Hospital, Incheon, Korea.
authors.forename: Heung Kyu
authors.initials: HK
authors.lastname: Park
keywords: Breast neoplasms; Ki-67 antigen; Neoadjuvant therapy; Predictive value of tests
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