Predicting Response to Neoadjuvant Chemotherapy in Women with Locally Advanced Breast Cancer in Kenya: Utility of Ki67

Background: Ki67 levels have been shown to have good predictive value in breast cancer treatment. There is paucity of data on Ki67 levels in predicting response to neoadjuvant chemotherapy (NACT) in Kenya. This study evaluated the utility of Ki67 in predicting response to NACT. Methods: This was a prospective observational study carried out at Kenyatta National Hospital between December 2017 and January 2019 onpatients with locally advanced breast cancer. We recruited 61 women through consecutive sampling technique. Data collected included patient demographics, pre-treatment tumor size, Ki67 levels and tumor biology. After 3 cycles of first-line chemotherapy, ultrasonography was used to determine response. Data were analyzed by SPSS for proportion of change in tumor size. The response was correlated with tumor biology and pretreatment levels of Ki67 using chisquare at a 95% confidence interval. A p-value <0.05 was considered statistically significant. Results: The response rate after 3 cycles of NACT was 39.4%, sensitivity and specificity of Ki67 levels were 70.8% and 43.2% respectively with a cut-off value of 32.5%. Conclusions: Ki67 was found to predict response in our context at a rate of 39.4% at 20% cutoff after 3 cycles. Keywords: Ki67, Breast cancer, Neoadjuvant chemotherapy