c-erbB-2 oncoprotein: A potential biomarker of advanced prostate cancer

BACKGROUND. Overexpression of the c-erbB-2 oncogene has been implicated in the development and/or prognosis of several human carcinomas, including that of the prostate. Recently, c-erbB-2 protein was found to be released in the circulation. The present study was undertaken to study the significance of serum c-erbB-2 protein determination in men with prostate cancer. METHODS. Serum c-erbB-2 protein determination was performed via immunoradiometric assay using two monoclonal antibodies that react with the extracellular domain of the protein. The study population consisted of 71 untreated prostate cancer patients. Of those, 33 with stage D2 disease entered a follow-up study. As control, serum c-erbB-2 protein levels were determined in 92 patients with benign prostatic hypertrophy. In addition, elevations of c-erbB-2 protein were examined in patients with various disease statuses: clinically well controlled (28 patients), disease progression (24 patients), and end-stage disease (17 patients). RESULTS. Elevation of serum c-erbB-2 protein level was observed in patients in advanced stages, such as stage D2 disease (30%), disease progression (42%), and end-stage disease (82.4%). In the follow-up study, patients with an elevated c-erbB-2 level had a significantly shorter interval to disease progression than did those with a normal level. CONCLUSIONS. The results suggest that c-erbB-2 can be used as a biomarker to identify a malignant subgroup in prostate cancer. (C) 1997 Wiley-Liss, Inc.