This should of course be considered in coordination with other histopathological variables and the patient’s clinical history, and the IKWG does not recommend the use of Ki-67 to withhold chemotherapy based on a low Ki-67 in patients with a poor anatomic prognosis (i.e., positive nodes, large tumor size, etc.), even if they have a favorable biology (i.e., ER rich, HER2 negative) [2]. This evidence concerns the gene MKI67 and neoplasm.