Study to Evaluate Real-world Effectiveness With Palbociclib Plus Endocrine Therapy as First-line/Second-line Treatment for HR+/HER2- Advanced Breast Cancer in Japan

Prior treatment

• Patients who received chemotherapy as first line treatment.
• Patients who have previously participated or are participating in any interventional clinical trials that include investigational or marketed products.
  • (Interventional clinical trials for early breast cancer and later line after palbociclib will be acceptable, Besides, patients participating in other investigator-initiated research or noninterventional studies can be included as long as their standard of care is not altered by the study.)

• Diagnosis of HR+/HER2- ABC
• Age of 20 years or older at diagnosis of ABC
• Patients that received palbociclib plus ET in the first line or second line
• Patients who meet the criteria regarding the medical record below:
• Patients with any medical records (regardless of palbociclib use) for more than 6 months from palbociclib initiation OR
• Patients with any medical records for less than 6 months from palbociclib initiation AND who had specific events (death, disease progression, or treatment discontinuation of palbociclib due to adverse events) in the available records