Serial serum c-erbB-2 levels in patients with breast carcinoma

BACKGROUND. Recently, the extracellular domain of the c-erbB-2 oncogene product (HER-2/neu) has been reported to be elevated in the serum of one- fourth of patients with metastatic breast carcinoma. The role of serum c- erbB-2 as a tumor marker, however, is still poorly defined. The purpose of this study was to evaluate the utility of serial serum c-erbB-2 levels as a tumor marker in patients with metastatic breast carcinoma. METHODS. c-erbB-2 levels in the sera of patients with breast carcinoma were determined by an enzyme immunoassay that detects the extracellular domain of c-erbB-2. Serum c-erbB-2 levels were evaluated prior to treatment as well as throughout the course of treatment with second-line hormonal therapy employing either megestrol acetate or fadrozole, an experimental aromatase inhibitor. RESULTS. Fifty-eight of 300 patients (19.3%) had elevated pretreatment serum c-erbB-2 levels. Of these 58 patients with elevated pretreatment c-erbB-2, 48 had more than 1 visit which enabled us to quantitate serial c-erbB-2 levels throughout tire course of treatment. Of these 48 patients, 28 (58.3%) had serial c- erbB-2 values that correlated with the clinical course. CONCLUSIONS. Serial serum c-erbB-2 levels did not show a high overall correlation with the clinical course in this group of patients with metastatic breast carcinoma treated with second line hormonal therapy.