MKI67 and breast cancer: In all, there were 1201 scorable cases in the validation set of the BC Cancer series, of which 23.1% (277/1201) were positive for CSF-1R expression on carcinoma cells, and high expression was significantly associated with tumor size > 2 cm, grade 3 histology, Ki67 index ≥ 14%, negative hormone receptor status, HER2 positivity, and non-luminal subtypes (Table 1).