Study to Evaluate Overall Survival in Japanese Patients With HR+/HER2- Advanced Breast Cancer Treated With Palbociclib Plus Letrozole

Retrospective, Multicenter, Observational Study to Evaluate Overall Survival in Japanese Patients With HR+/HER2- Advanced Breast Cancer Treated With Palbociclib Plus Letrozole

This is a retrospective, multicenter, observational study in Japan. The primary objective is to evaluate overall survival (OS) in Japanese patients with HR+/HER2- advanced breast cancer who have been treated with palbociclib plus letrozole. This observational study was planned as follow-up study of Japanese phase 2 study of palbociclib (NCT01684215, phase 2 portion of A5481010 study).

Inclusion Criteria:

1. Participated, treated with palbociclib plus letrozole in J-Ph2, and was under follow-up for survival at the study completion of J-Ph2.
2. For patients who are still alive and have routine visits to the study site, evidence of a personally signed and dated informed consent document indicating that the patient has been informed of all pertinent aspects of the study. For patients who are still alive and had been transferred to another hospital, evidence that the patient has been informed of all pertinent aspects of the study and oral or written informed consent is obtained. For patients who had already passed away, the conduct of this study will be disclosed, and the patients' legally acceptable representatives will be guaranteed an opportunity to refuse data collection for the patients in accordance with the Ethical Guidelines for Medical and Health Research Involving Human Subjects

Exclusion Criteria:

1. There are no exclusion criteria for this study.