Impact of Serum HER2 Levels on Survival and Its Correlation with Clinicopathological Parameters in Women with Breast Cancer

PURPOSE: The aims of our study were to assess the correlation between serum HER2 and clinicopathologic factors, the effect of serum HER2 on survival rate, and the effect of changes in serum HER2 levels between pre- and post-adjuvant chemotherapy on survival rate. METHODS: The study subjects, 200 women with breast cancer, were a subset of patients operated on between January 2005 and December 2006. We evaluated changes in serum HER2 levels between pre- and post-adjuvant chemotherapy. RESULTS: Being estrogen receptor (ER) negative was also correlated with high serum HER2 (p=0.017). The number of patients with changes in serum HER2 (>20% increased level during the follow-up period) was correlated with advanced T-stage (p=0.010), advanced American Joint Committee on Cancer (AJCC) stage (p=0.015) and poor histologic grade (p=0.001). Univariate analysis for prognostic factors associated with disease-free survival (DFS) revealed that the difference in DFS between those with serum HER2 level <15 ng/mL and those with levels ≥15 ng/mL was statistically significant (p=0.0129) and the changes in serum HER2 levels were also statistically significant (p=0.001). Prognostic factors associated with overall survival revealed that the changes in serum HER2 levels between pre- and post-adjuvant chemotherapy were statistically significant (p=0.0012). CONCLUSION: Serum HER2 level is associated with a more advanced degree of axillary lymph node involvement and associated with ER negativity. And Changes in serum HER2 levels are associated with more advanced AJCC staging and histologic tumor grade. There are significant associations between serum HER2 level, changes in serum HER2 levels and 5-year DFS.