Correlation between serum HER-2 oncoprotein and patients with breast cancer

Objective: 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 immunosorbent 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 disease, 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.