MKI67 and breast cancer: Similar to hormone receptors and HER2, changes in Ki-67 have been reported following neoadjuvant chemotherapy, with reports suggesting that about two thirds of cases showing a decrease in Ki-67, one fourth of cases showing an increase, and the rest showing no change, with exact percentages varying depending on the distribution of breast cancer subtypes and type of neoadjuvant chemotherapy being used [89,90,91,92].