Prospective Study Assessing EndoPredict® Genomic Test Impact on Shared Decision of Adjuvant Chemotherapy in Patients With ER-positive, Her2-negative Early Breast Cancer

Inclusion Criteria: * Age ≥ 18 years, * Performance status 0 or 1, * Patient with newly diagnosed, previously untreated, unilateral, localized, histologically confirmed, invasive breast cancer * Fully operated breast cancer including complete resection of breast tumor and adequate axillary surgery * Available surgical material (formalin-fixed, paraffin-embedded) for EPclin® evaluation * ER-positive by IHC (\>10% cells stained or Allred Score≥4) * HER2-negative by IHC (score 0 or 1+) and/or Fish/Cish * Node-negative or pN1mi (through axillary lymph node examination using sentinel node biopsy or axillary clearance) * Uncertainty regarding the toxicity/benefit of adjuvant chemotherapy, outlined inthe following situations: * Lobular histology * Or grade II * Or grade III and pT \< 2cm * Adequate renal, hepatic, cardiac and hematopoietic functions for a chemotherapy administration * Willingness and ability to comply with scheduled visits as well as with test results and chemotherapy decision according to the latest * Signed informed consent and Health insurance coverage Exclusion Criteria: * Non operable, bilateral, locally advanced, T4 or metastatic breast cancer * Any lymph node involvement with the exception of pN0i+ or pN1mi * HER2 Overexpression * Diagnosis of any previous malignancy within the last 5 years, except for adequately treated basal cell carcinoma, or squamous cell skin carcinoma, or in situ cervical carcinoma * Any previous systemic or locoregional treatment for the present breast cancer * Documented inherited predisposition with BRCA1/2 or TP53 mutation * Previous hormone replacement therapy (HRT) stopped less than 2 weeks before surgery * Previous treatment for the present breast cancer * Person unable to give informed consent