Triple-­‐negative breast cancer (TNBC) is a heterogeneous breast cancer subgroup with lacking of tumor markers, which lead to limitations in its treatment options and a consequent adverse prognosis. For this, the absence of effective targeted therapies requires new biomarkers to develop therapeutic strategies in the futureFatty acid synthase (FASN), which is overexpressed in several human carcinomas including triple-­‐negative cell lines, could be a potential novel biomarker and a therapeutic target or co-­‐target in TNBC. Main objective: To characterize FASN expression levels in TNBC patient tissue samples, compared to FASN expression levelsin non-­‐tumoral breast tissue samples, obtained between 1990 and 2012 from oncologic patients of Institut Català d’Oncologia (ICO) in Hospital Universitari de GironaDr. Josep TruetaDesign: Cross-­‐sectional study conducted between January 2014 and December 2014Methods: One hundred and four TNBC tissue samples have been analysed and gradedaccording to FASN expression levels by immunohistochemistry methods, and subsequently classified in two categories: low (0+/1+) and high (2+/3+) expression ofFASN. In parallel, clinical records from 90 TNBC patients have been collected, and clinical and histopathological characteristics of these patients have been described besides evaluating its association with the corresponding FASN expression results