Epidemiology and Treatment of HR+/HER2- Breast Cancer in England

Inclusion criteria: * Patient with a registered diagnosis of International Classification of Diseases,10th Revision (ICD-10) code C50: malignant neoplasm of the breast, between 01 April 2012 and 31 December 2022. * Patient ≥18 years of age at diagnosis. * Patient with estrogen receptor-positive (ER+) or progesterone receptor-positive (PR+), i.e., hormone receptor positive (HR+) breast cancer * Patient with human epidermal growth factor receptor 2 negative (HER2-) breast cancer. Additional inclusion criteria for patients with metastatic BC were defined as: * Tumor stage IV at diagnosis or on subsequent treatment or * Tumor Node Metastases (TNM) staging indicative of M1 at diagnosis or on subsequent treatment or * Record with ICD-10 codes indicating secondary malignant neoplasm C77\* (excluding C771 and C773), C78\*, or C79\* or * Initiation of treatment specified for metastatic BC, defined as ribociclib or palbociclib from 01 January 2017 to the end of the study period or abemaciclib from 01 January 2017 to 31 May 2022 or * Record of treatment for distant/metastatic recurrence. An additional inclusion criterion for patients with early BC was: • No evidence of metastatic disease (defined above) before or up to 100 days after the first BC diagnosis date. Additional inclusion criteria for patients in the NATALEE Trial-aligned sub-cohort: * Patient with stage IIa BC at diagnosis (i.e., T0-1 N1 or T2 N0 with Grade 3 tumor), or * Stage IIb BC at diagnosis (i.e., T2 N1, T3 N0)…