Analyses on other subgroups were concordant: IDC-DCIS comprised large IDC (⩾1.8 cm) with small DCIS (<1.5 cm) correlated with higher Ki-67 levels than IDC-DCIS with small IDC (<1.8 cm) and large DCIS (⩾1.5 cm), which in turn had higher Ki-67 levels than pure DCIS (correlation coefficient, −0.2; P<0.005). Here, MKI67 is linked to ductal breast carcinoma in situ.