The study is a retrospective and prospective, non-interventional, observational registry-based study that will enroll all patients with ER +/HER2-negative, T1-3 breast cancer with negative axillary lymph nodes or up to 3 positive axillary lymph nodes for whom Breast Units require genomic test to support adjuvant therapy decisions, according to current clinical practice. For prospective cohort: genomic tests will be performed on all patients who meet the criteria for access to testing as set out in the Ministerial Decree of 18/05/2021, unless otherwise agreed by the reference Breast Unit, in accordance with the specific diagnostic pathways activated by each site. For retrospective cohort: data for patient referred for genomic testing following Ministerial Decree 18/05/2021 will be collected. The patient's baseline demographic characteristics, tumor clinicopathological features, pre and post-test therapeutic indication (CET vs ET), the test results, the actual adjuvant treatment received and time around data will be recorded in a dedicated registry.
