Estrogen Receptor, c‐erbB‐2 and nm23/NDP Kinase Expression in the Intraductal and Invasive Components of Human Breast Cancers

Expression of the c‐erbB‐2 oncoprotein (ErbB‐2) and the nm23 anti‐metastatic gene product (nucleoside diphosphate [NDP] kinase) was examined in the intraductal and invasive components of 63 fresh human breast cancer tissues. The expression of estrogen receptor (ER) as a marker of hormone dependency and the Ki‐67 protein as a proliferative cell marker was also examined. ErbB‐2 and ER were positive in 77.8% (28/36) and 64.7% (22/34) of the intraductal components, and in 43.6% (27/62) and 57.1% (36/63) of the invasive components, respectively. NDP kinase was positive in 58% (18/31) of intraductal, and in 30.9% (17/55) of invasive areas. The average Ki‐67‐positive cell rates were 5.9% in the intraductal, and 10.7% in the invasive components. Thus, the cells within the intraductal component of breast cancer appear to have different characteristics from the invasive component, not only in markers of proliferative ability, but also in the expression of oncogenes and hormone receptors.