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

Purpose: 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).

Methods: 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.

Results: 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.

Conclusion: High value of Ki67 is a negative predictor for response in concurrent capecitabine-radiotherapy treatment in chemo-resistant advanced breast cancer.