DETERMINATION OF CYTOSOL C-ERBB-2 PROTEIN IN BREAST-CANCER BY SANDWICH ENZYME-IMMUNOASSAY

We determined cytosol c-erbB-2 protein levels using a sandwich enzyme immunoassay in benign breast disease and primary and recurrent breast cancer and analyzed the relationship between c-erbB-2 protein levels a nd clinicopathological factors. Overexpression of c-erbB-2 protein, th e cut-off value being set at 18 ng/mg protein, was observed in 26 of t he 139 cases of stages I-IIIB breast cancer (18.7%), four of the 12 ca ses of stage IV breast cancer (33.3%) and seven of the 13 recurrent br east cancer cases (53.8%). The levels of c-erbB-2 protein were signifi cantly different between the stages. Overexpression of c-erbB-2 protei n in stages I-IIIB breast cancer was associated with histological grad e and serum CEA level, but not with other clinicopathological factors. In addition, there was an inverse correlation in the group of stages I-III plus IV breast cancer between c-erbs-2 protein expression and es trogen receptor status. Overexpression of c-erbB-2 protein can be easi ly determined in the cytosol fraction together with hormonal receptor by this method. The prognostic importance will be evaluated in ongoing adjuvant trials for operable breast cancer patients.