MKI67 and breast cancer: In luminal B breast cancer, Cox regression analysis that included other prognostic factors, such as, age, T factor, N factor, nuclear grade, PgR positivity, and Ki67 index, showed that TOP2A overexpression was the strongest prognostic factor for RFS (hazard ratio [HR] 4.00, 95% confidence interval [CI] 1.65–9.54, p < 0.001) (Table 3).