Background: Various methods and criteria are used to determine protein overexpression of c-erbB-2 and the clinical utility of c-erbB-2 is under investigation. We have reported previously that the levels of cytosol c-erbB-2 in breast cancer were significantly different between the clinical stages.
Methods: The levels of c-erbB-2 protein were determined in sera from 210 breast cancer patients using a sandwich enzyme immunoassay between November 1996 and March 1998. The cut-off level was set at 5.4 ng/ml for healthy female blood donors.
Results: First, serum c-erbB-2 levels were analyzed in 73 preoperative breast cancer patients with stage I-IIIB disease. The range and median values were 2.3-32.3 and 4.8 ng/ml, respectively. The positive rate was 38%. Overexpression of serum c-erbB-2 was significantly associated with tumor size, clinical stage, histological grade, lymphatic invasion, nodal status and overexpression of cytosol c-erbB-2, but not with hormonal receptor status and other clinico-pathological factors. Second, c-erbB-2, CEA and CA15-3 in sera were examined in 157 postoperative breast cancer patients. In the 137 disease-free patients, specificities of c-erbB-2, CEA and CA15-3 were 72, 93 and 99%, respectively, but in the 20 first recurrent patients, these sensitivities were 80, 25 and 25%, respectively.
Conclusions: These results suggest that serum c-erbB-2 protein is a useful marker for predicting aggressive behavior and first recurrence of breast cancer.