Prognostic and predictive value of c-erbB-2 overexpression in primary breast cancer, alone and in combination with other prognostic markers.

PURPOSE: To investigate the prognostic and predictive value of c-erbB-2 overexpression in breast cancer in relation to other prognostic markers. PATIENTS AND METHODS: Paraffin-embedded tumors from 315 consecutive primary breast cancer patients were screened for c-erbB-2 protein (p185) overexpression by immunohistochemistry using the monoclonal antibody CB11.
RESULTS: c-erbB-2 protein overexpression was detected in 19% of tumors and was associated with shorter 5-year overall survival (OAS) rate compared with c-erbB-2-negative cases in the total patient material (58% and 77%, respectively; P = .004) and in the 96 node-positive patients (31% and 61%, respectively; P = .02), but not in node-negative patients. For 47 node-positive patients treated with adjuvant tamoxifen and radiotherapy, the 5-year OAS was 13% for c-erbB-2 overexpression and 75% for c-erbB-2-negative patients (P = .00004). The frequency of c-erbB-2 overexpression decreased with age at diagnosis. The prognostic value of c-erbB-2 on OAS was independent of age, node status, tumor size, histopathologic grade, hormone receptor status, S phase, p53 status, and adjuvant treatment. c-erbB-2 status added prognostic information to p53-negative and low S-phase cases, but not to p53-positive and high S-phase cases. Correspondingly, these only added information to c-erbB-2-negative cases.
CONCLUSION: c-erbB-2 protein overexpression may have a predictive value with regard to adjuvant therapy in node-positive patients, for whom adjuvant tamoxifen with radiotherapy appears insufficient in the presence of c-erbB-2 overexpression. Combination of conventional and newer tumor markers may identify patients with a worse prognosis within groups with a generally favorable prognosis.