MKI67 and breast cancer: Breast cancer (BC) is the most common malignant tumor among woman worldwide, with an estimated 2.3 million new cases and 6,65,684 deaths in 2022, posing a serious threat to women’s health.[1] BC has various pathological types, high incidence, significant tumor heterogeneity, complex mechanisms of occurrence.[2] Traditional clinical subtypes of BC are classified by histological characteristics and the expression of ER, PR, HER2, and Ki-67, resulting in ER-positive, HER2-positive, and triple-negative breast cancer categories.