Prognostic significance of c-erb B-2 protein status using an enzyme immunoassay in breast cancer

Abstract

Background. The prognostic significance of c-erb B-2 in breast cancer remains controversial. The aim of this study was to determine the practical prognostic significance of c-erb B-2 protein status in breast cancer extracts, using an enzyme immunoassay. Methods. An enzyme immunoassay was used to measure levels of c-erb B-2 protein prospectively in 360 patients with breast cancer, using cytosol fractions prepared for steroid receptor assay. The status of c-erb B-2 protein was assessed using a cut-off value for positivity of 18 ng/mg protein. Univariate and multivariate analyses were performed. To evaluate the prognostic significance of c-erb B-2 protein status. Results. Levels of c-erb B-2 protein in tumor tissue extract ranged from 0 to 213.0 ng/mg protein (mean, 15.5 ng/mg protein). In 52 tumors (14.4 %) more than 18.0 ng/mg protein was detected, and these tumors were regarded as c-erb B-2 protein-positive. Correlations were found between c-erb B-2 protein positivity and large tumor size (>3 cm; P = 0.0095), higher histological grade (P < 0.0001), estrogen receptor negativity (P < 0.0001), and progesterone receptor negativity (P < 0.0001). There was also a marginally significant correlation between c-erb B-2 protein positivity and lymph node positivity. Multivariate analysis showed that c-erb B-2 protein status was a significant independent prognostic factor for disease-free survival, being strongly significant in patients with positive lymph nodes. Conclusion. c-erb B-2-positive breast cancers are biologically more aggressive and c-erb B-2 protein status could be a candidate as a prognostic factor for patients with breast cancer, being particularly valuable in patients with positive lymph nodes.