Ki-67 Change in Anthracyline-containing Neoadjuvant Chemotherapy Response in Breast Cancer

Objective: Anthracycline-containing regimens are irreplaceable in neoadjuvant chemotherapy (NAC) for breast cancer (BC) at present. However, 30% of early breast cancer (EBC) patients are resistant to anthracycline-containing chemotherapy, leading to poor prognosis and higher mortality. Ki-67 is associated with the prognosis and response to therapy, and it changes after NAC. Methods: A total of 105 BC patients who received anthracycline-containing NAC were enrolled. Then, the optimal model of Ki-67 was selected, and its predictive efficacy was analyzed. Immunohistochemistry (IHC) was used to determine the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER-2) status and Ki-67 level. Fluorescent in situ hybridization (FISH) was used to verify the HER-2 when the IHC score was 2+. Results: The post-NAC Ki67 level after treatment with anthracycline drugs was lower than pre-NAC Ki-67 (19.6%+/- 23.3% vs. 45.6%+/- 23.1%, P<0.001). Furthermore, patients with the Ki-67 decrease had a border line higher pathological complete response (pCR) rate (17.2% vs. 0.0%, P=0.068), and a higher overall response rate (ORR) (73.6% vs. 27.8%, P<0.001), when compared to patients without the Ki-67 decrease. The Delta Ki-67 and Delta Ki-67% were valuable markers for the prediction of both the pCR rate and ORR. The area under the curve (AUC) for Delta Ki-67 on pCR and ORR was 0.809 (0.698-0.921) and 0.755 (0.655-0.855), respectively, while the AUC for Delta Ki-67% on pCR and ORR was 0.857 (0.742-0.972) and 0.720 (0.618-0.822), respectively. Multivariate logistic regression model 1 revealed that Delta Ki-67 was an independent predictor for both pCR [odds ratio (OR)=61.030, 95% confidence interval (CI)=4.709-790.965; P=0.002] and ORR (OR=10.001, 95% CI: 3.044-32.858; P<0.001). Multivariate logistic regression model 2 revealed that Delta Ki-67% was also an independent predictor for both pCR (OR=408.922, 95% CI=8.908-18771.224; P=0.002) and ORR (OR=5.419, 95% CI=1.842-15.943; P=0.002). Conclusions: The present study results suggest that Delta Ki67 and Delta Ki67% are candidate predictors for anthracycline-containing NAC response, and that they may provide various information for further systematic therapy after surgery in clinical practice.