The Correlation of Serum HER-2/neu and CA15-3 in Patients with Metastatic Breast Cancer / 한국유방암학회지

ABSTRACT

PURPOSE: The extracellular domain (ECD) of the HER-2/neu oncoprotein, whose molecular weight is the range from the 95 kD to 105 kD, is shed into the blood from the cell surface via, proteolysis by a metalloprotease. A monoclonal antibody immunoassay has been developed for measuring the circulating concentrations of serum HER-2/neu ECD (following serum HER-2/neu). Serum HER-2/neu has been reported to be correlated with an increased tumor volume in those patients suffering with breast cancer. We measured the serum CA15-3 level, which is a surrogate marker of the tumor burden, we analyzed the correlation of the serum CA15-3 with the serum HER-2/neu and we analyzed the association of both markers with the clinical outcomes. METHODS: The sera for the analysis of both HER-2/neu and CA15-3 were obtained from 99 healthy Korean women, 66 primary breast cancer patients and 43 metastatic breast caner patients. The serum HER-2/neu level was measured quantitatively with using an ADVIA Centaur(R) automated immunoassay analyzer (Bayer Health Care LLC, Diagnostics Division, Tarrytown, New York, USA) and the CA 15-3 level was measured via radioimmunoassay. RESULTS: The serum HER-2/neu level was increased 23 metastatic cancer patients (53%). On the analysis of the correlation of serum HER-2/neu and CA15-3, the correlation coefficient (r) was 0.8072. Thus a positive serum HER-2/neu test in breast cancer patients was highly associated with the CA15-3 level for assessing whether metastasis was present or not. For the relationship between primary breast cancer and metastatic breast cancer, the former was classified as the control group and the latter as the patient group. The results of the Receiver Operation Characteristic (ROC) curve for serum HER-2/neu and CA15-3 showed no statistically significant differences (p=0.176) but the diagnostic efficacy of the serum HER-2/neu test was measured more exactly than that of CA15-3 and CA15-3 a tool for measuring a tumor marker for the diagnosis of whether metastasis was present or not. CONCLUSION: Serum HER-2/neu is a significant independent predictive prognostic factor for metastatic breast cancer patients. In view of the results we have achieved so far the serum HER-2/neu level in metastatic breast cancer patients may play an important roll as an independent tumor marker.