1. Women of 18 years of age with proven diagnosis of advanced adenocarcinoma of the
breast (locoregionally recurrent or metastatic disease).
2. ER+ and/or PgR+ tumor based on local laboratory results :test as per local practice
3. HER2- breast cancer based on local laboratory results :test as per local practice or
local guidelines
4. Patients must be appropriate candidates for hormone therapy.
5. Evidence of a personally signed and dated informed consent document indicating that
the patient or a legally acceptable representative has been informed of all pertinent
aspects of the study.
1. Any patients who does not agree that Pfizer and companies working with Pfizer use
his/her information
2. Known hypersensitivity to letrozole or its excipients or to any CDK4/6 inhibitor
excipients.
3. Pregnant women