This observational study is restricted to postmenopausal women with hormone-sensitive early breast cancer, who have decided to take prescribed adjuvant use of AIs, anastrozole or letrozole, according to the current product SmPCs. There is no Investigational Medicinal Product (IMP) to be taken in this observational study. The adjuvant AI medication must not have exceeded thirteen weeks. In CARIATIDE (Compliance of ARomatase Inhibitors AssessmenT In Daily practicE through Educational approach), impact of educational material on women's compliance and persistence rates will be evaluated.