For patients with HR+ breast cancer, the MonarchE (38) study reaffirmed the place of abemaciclib in combination with tamoxifen or an aromatase inhibitor or in the adjuvant treatment of HR+/HER2−breast cancer, especially for adjuvant intensification in high-risk breast cancer (level of evidence: 1A). This evidence concerns the gene CYP19A1 and breast carcinoma.