MKI67 and breast cancer: The DDFS durations of the 1,721 women with intermediate Ki-67 expression and high PgR levels (that is, those who were reclassified as having luminal A–like instead of luminal B–like breast cancer according to the 2013 definitions) were significantly better than those of the remaining 555 women with intermediate Ki-67 expression and low PgR levels (HR = 1.86, 95% CI = 1.37 to 2.52; P < 0.001 by Gray test) (Figure 2b).