The breast cancer patients with brain metastasis and Ki-67 of ≤ 40% in the primary lesions had a longer brain metastasis-free survival compared to those with Ki-67 of > 40% in the primary lesions (45.0 vs. 32.0 months, P = 0.19) (Figure 7), although no statistical difference was found. This evidence concerns the gene MKI67 and breast carcinoma.