ERCC1 expression in triple negative breast cancer

Purpose: Excision repair cross-complementation group 1 (ERCC1), which is a component of nucleotide excision repair (NER) pathway, removes platinum-induced DNA adducts. Overexpression of ERCC1 has been associated with resistance to platinum-based chemotherapy in ovarian and lung cancers. Detecting ERCC1 overexpression is important in considering treatment options for triple negative breast cancer (TNBC), and in conducting and interpreting trials that search to find specific chemotherapy regimens for TNBC. In this study we aimed to study ERCC1 overexpression in patients with TNBC. Methods: A monoclonal antibody against ERCC1 was used for immunohistochemical (IHC) analysis of tumor samples. Tumor samples from 45 patients were evaluated by two experienced pathologists who were blinded to clinical data. A semi-quantitative H score (intensity staining scale ranging from no staining/0 to very intense staining/3 ⁺) was calculated by multiplying staining intensity with extent score. Tumors with H score ≥ 1 were classified as ERCC1-positive. Results: ERCC1 expression was positive in 73.3% of the tumor samples with an H score ≥ 1 and 26.7% of the tumor samples stained negative with an H score < 1. Of the tumor samples 15.5% stained diffusely and intensively. Conclusion: Our study demonstrated that about two thirds of the TNBC showed positive expression of ERCC1, which may be predictive of a poor response to platinum-based chemotherapy.