Expression of E26 transformation specific-1 (ETS-1) in tumour-infiltrating lymphocytes (TILs) is adverse prognostic factor in invasive breast cancer

Abstract

AIM OF THE STUDY: The microenvironment depicts the relationship between tumour cells and immune response, and every insight into stromal lymphocytes could contribute to explain their role and activity. E26 transformation specific-1 (ETS-1) is a transcription factor that is active in cell proliferation. We analysed its immunohistochemical expression in tumour infiltrating lymphocytes (TILs) in invasive breast cancer and correlated its immunohistochemical score (IHS) to traditional predictive and prognostic factors and survival. MATERIALS AND METHODS: The sample contains data of 121 patients with invasive breast cancer, not otherwise specified (NOS) who underwent mammectomy and lymphadenectomy in 2002 at the Clinical Hospital Centre Zagreb, Croatia. Paraffin blocks of the tumour tissue were collected from the pathological archive. Three representative areas of every patient were chosen and multiple tissue samples were made. Immunohistochemical staining with rabbit anti-ETS-1 (Novocastra, UK) and the ABC method was performed on a DAKO Autostainer. The expression of ETS-1 in stromal TILs was analysed on an Olympus 41 microscope. The IHS score was calculated and correlated with clinical and pathological parameters, as well as disease-free survival (DFS) and overall survival (OS). RESULTS: In almost all patients (95%), some expression of ETS-1 in TILs was found. A moderate/high score of ETS-1 correlated with larger tumour size and higher histological grade, high proliferation index and low progesterone receptors (PgR). The patients with moderate/high ETS-1 expression in TILs had shorter DFS than patients with weak/negative ETS-1 expression. CONCLUSION: In invasive breast cancer NOS, expression of ETS-1 in TILs is an adverse prognostic factor.