[Utility of serum human epidermal growth factor receptor-2 extracellular domain(HER2 ECD)assessment in patients with advanced or recurrent breast cancer and those who received neoadjuvant therapy].

Levels of serum human epidermal growth factor receptor-2 extracellular domain(HER2ECD )were measured in breast cancer patients. Fifty-six patients had advanced or recurrent disease, and 21 others were preoperation patients who received neoadjuvant therapy. In the tissue HER2-positive group of advanced or recurrent patients, levels of serum HER2ECD at first recurrence were high(≥15. 3 ng/mL)in 75%of patients, and significantly higher(p=0. 03)than in the tissue HER2-negative group. In neoadjuvant therapy patients, the levels of serum HER2ECD were high in 50% of the tissue HER2-positive group, and within the normal limit in all the tissue HER2-negative group(p=0. 015). The levels of serum HER2ECD were closely correlated with treatment efficacies in both recurrent and neoadjuvant patients. In this study, the levels of serum HER2 ECD appeared to be useful for diagnosis of recurrence in HER2-positive breast cancer and for estimation of therapy in recurrent and neoadjuvant patients as a secondary bio-marker.