To 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. Methods A 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 im-munosorbent assay （ELISA）. Results The 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 dise-ase

there was no correlation with site of metastases （P > 0.05）. Conclusion Serum 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.