Abstract
PurposeThis study evaluated the association of serum HER2 (sHER2) levels at diagnosis with clinicopathologic parameters and disease free survival (DFS) in operable breast cancer patients according to intrinsic subtype.MethodsThe sHER2 levels were measured using a chemiluminescence immunoassay. The HER2 status in all tumor tissues was determined by immunohistochemistry, and confirmed in equivocal cases by fluorescence in situ.ResultsThere were 436 consecutive stage I-III breast cancer patients with sHER2 result at diagnosis between Nov 2004 and Dec 2011. High sHER2 levels (≥ 15 ng/ml) were reported in 52 patients (11.9%) and HER2 overexpression in tumor tissue was observed in 111 patients (25.5%). High sHER2 levels were associated significantly with advanced stage (P < 0.001), mastectomy (P = 0.012), neoadjuvant chemotherapy (P < 0.001), anti-HER2 therapy (P < 0.001) and hormone therapy (P = 0.022). The patients with high sHER2 levels had a worse DFS (P < 0.001). In multivariate analysis, high sHER2 levels were associated significantly with worse DFS (HR = 2.25, 95% CI 1.27–3.99, P = 0.005). High sHER2 levels were associated with worse DFS in the HR+/HER2-, HR+/HER2+ and HR-/HER2+ subtypes (P = 0.043, 0.003 and 0.041, respectively).ConclusionsThese results show that the sHER2 level at diagnosis is a useful prognostic factor in patients with operable breast cancer, especially in the HR+/HER2-, HR+/HER2+ and HR-/HER2+ subtypes.
Highlights
The Her-2/neu proto-oncogene is located on chromosome 17q21 and encodes a transmembrane glycoprotein
High serum human epidermal growth factor receptor 2 (HER2) (sHER2) levels (! 15 ng/ml) were reported in 52 patients (11.9%) and HER2 overexpression in tumor tissue was observed in 111 patients (25.5%)
High sHER2 levels were associated significantly with worse disease free survival (DFS) (HR = 2.25, 95% CI 1.27–3.99, P = 0.005)
Summary
The Her-2/neu proto-oncogene is located on chromosome 17q21 and encodes a transmembrane glycoprotein. 15% to 30% of breast cancer tumors show over-expressed human epidermal growth factor receptor 2 (HER2) protein as a result of gene amplification. Overexpression or amplification of HER2 is associated with poor prognosis [1]. A humanized monoclonal antibody specific for HER2, became available as a treatment for HER2-positive breast cancer, HER2 status has become important in deciding whether to treat with trastuzumab [2]. To determine a patient’s HER2 status, immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) have been used. Both require a tissue sample, which is not always available. IHC has relatively low accuracy, and FISH is a costly procedure
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