More than 70% of patients with metastatic breast cancer (MBC) present with hormone receptor‐positive disease.1 Endocrine therapy is the recommended initial treatment for hormone receptor‐positive metastatic disease in the current guidelines, even with visceral metastases.2 Prospective trials have shown that endocrine therapy, such as fulvestrant with or without a CDK 4/6 inhibitor, may substantially improve progression‐free survival (PFS) with good patient tolerance.3, 4, 5, 6. This evidence concerns the gene NR4A1 and glycogen storage disease VI.