Breast cancer is a highly heterogeneous disease, classified by the TNM (T – tumour; N – lymph node metastasis; M – distant metastasis) system, histological grade and expression of hormone receptors (oestrogen – ER and progesterone – PR) and human epidermal receptor 2 (HER2) [1–4]. This evidence concerns the gene NR4A1 and breast carcinoma.