Regarded by many as the most critical single molecular prognosticator in breast cancer, even when compared with costlier multigene expression profiling [28], the Ki67 proliferative index is at once a negative correlate of disease-free survival and overall survival [29, 30] and a strong predictor of initial response to chemotherapy - although these inferences can only be applied to IDC at present. Here, MKI67 is linked to breast cancer.