According to the latest International Ki-67 in Breast Cancer Working Group (IKWG) consensus, identified in our search, Ki-67 cut-off values of ≤5% or ≥ 30% have validated prognostic value in estrogen receptor (ER) positive HER2 negative breast cancer, but are not established for the other subtypes. This evidence concerns the gene MKI67 and breast carcinoma.