Participants
Tumors, advanced/metastatic disease
ONCOLOGY, DISEASE, LYTIC BONE LESION, TUMORS
Men and postmenopausal women aged ≥ 18 years, with histologically or cytologically confirmed HR+/HER2− ABC (locoregionally recurrent or metastatic and not amenable to curative therapy) were eligible for the study. An Eastern Cooperative Oncology Group performance status of 0 or 1 and measurable disease according to Response Evaluation Criteria in Solid Tumors version 1.1 or at least one predominantly lytic bone lesion was required.Patients receiving treatment in the first-line setting were those with no prior treatment for ABC, including those who relapsed > 12 months after the end of (neo)adjuvant ET (late relapse) or patients with de novo advanced/metastatic disease (no prior exposure to ET). Patients characterized as receiving treatment in the second-line setting included those who relapsed ≤ 12 months from completion of (neo)adjuvant ET (early relapse) or progressed on first-line ET for ABC. Despite receiving treatment in the advanced setting for the first time, patients with early relapse were analyzed with the second-line population of patients due to having a more similar prognosis to this population compared with the otherwise defined first-line population in the study. Patients who had received previous chemotherapy for advanced disease or any previous treatment with fulvestrant or a CDK4/6i were not included.