Based on the suggestion that Ki67 may have prognostic and predictive value, the neoadjuvant Alliance ALTERNATE trial (NCT01953588) utilises changes in Ki67 after 1 month of endocrine therapy as a decision tool for subsequent continuation of endocrine therapy or switch to chemotherapy in postmenopausal women with ER positive primary breast cancer. This evidence concerns the gene MKI67 and breast carcinoma.