OBJECTIVETo detect serum HER-2 oncoprotein levels in patients with operable and metastatic breast cancers, and to study the correlations between serum HER-2 level and lymph node status as well as other clinical parameters.

METHODSA total of 120 women were studied consisting of 10 healthy volunteers, 31 benign breast disease, 53 operable breast cancer, and 26 metastatic breast cancer patients. The levels of serum HER-2 were measured using an enzyme-liked immunosorbent assay (ELISA).

RESULTSThe mean serum HER-2 levels were 9.6 +/- 1.5 ng/mL in healthy volunteers, 11.9 +/- 1.6 ng/mL in benign breast disease, 13.2 +/- 4.2 ng/mL in operable breast cancer, and 30.5 +/- 30.8 ng/mL in metastatic breast cancer patients. The former is much lower than the latter three (P = 0.02, 0.001, 0.03, respectively). If using 15 ng/mL as a normal baseline, elevated serum HER-2 levels were observed in none of the healthy volunteers as well as patients with benign disease, but in 18.9% (10/53) operable breast cancer patients and 61.5% (16/26) metastatic patients. In patients with operable breast cancer, there was a positive correlation between serum concentrations of HER-2 and the size of primary tumor (P < 0.05), whereas there was no correlation between serum concentration and axillary lymph node or estrogen receptor status. In patients with metastatic disease, there was no correlation with site of metastases (P > 0.05).

CONCLUSIONSerum HER-2 level was strongly correlated with tumor loads and clinical stages, thus acting as a promising predictor of cancer recurrence in breast cancer patients.