Comparative Effectiveness of PAL Based-therapy as Initial ET Versus PAL Based-therapy After ChT for HR+/HER2- ABC

This study is designed to be a multi-center non-interventional observational study led by the Cancer Hospital Chinese Academy of Medical Sciences. The target populations of this study are patients with HR+/HER2- advanced breast cancer who received palbociclib based-therapy as initial endocrine therapy or palbociclib based-therapy after chemotherapy from August 1, 2018 to December 31, 2023. It is expected to enroll 400 subjects in this study. The subjects' data such as demographics and other baseline characteristics, medications, prognosis, will be collected in a mixed manner, and statistical analysis of data will be conducted to compare the effectiveness outcome measures.