High Ki67 as negative predictor for response to concurrent radiotherapy plus Capecitabine in chemo-resistant advanced breast cancer.

The purpose of this study was to evaluate Ki67 as a biomarker for response to concurrent chemo-radiotherapy in previously treated patients with standard chemotherapy protocols in the neoadjuvant setting (NACT). Evaluated were 33 patients treated concurrently with radiotherapy and capecitabine. All patients had residual disease after anthracycline-docetaxel based NACT, verified with imaging techniques and clinical exams. Response rate (RR) was evaluated 3 months after completion of the concurrent treatment, and was correlated to tumor immune-histochemical characteristics. Binary logical regression was used for model testing and correlation of Ki67 and RR. An Omnibus test showed the model to be statistically significant and that a set of depending variables can be used as predictors for treatment response with p=0.021. Model -2 log likelihood with Nagelkerke R Square were used to define significance of other tumor characteristics besides Ki67. Only Ki67 showed statistically significant correlation with RR, as high Ki67 predicts that there will be no response to concurrent capecitabine - radiotherapy treatment in chemo-resistant advanced breast cancer. Other characteristics such as histological grade, estrogen or progesterone receptors, HER2 overexpression or lymphovascular or perineural invasion showed no significance. High value of Ki67 is a negative predictor for response in concurrent capecitabine-radiotherapy treatment in chemo-resistant advanced breast cancer.