Tan et al [53] demonstrated that increased levels of Ki 67 show a correlation with immuno-negativity for estrogen receptors, high tumor grade and increased mitotic activity, while in another study Kuroda et al [54] showed high levels of Ki-67, p-53 and P-glycoprotein more in basal than in non basal types of breast cancer. This evidence concerns the gene ESR1 and neoplasm.