Patients with endocrine responsive early stage postmenopausal breast cancer. Patients who
received tamoxifen for 2-3 years as adjuvant endocrine therapy. Patients who were approved
to switch to aromatase inhibitor treatment during the patient recruitment period.
Patients who were informed about the study and accepted to participate.
Patients having a psychological disorder which will prevent their understanding of
questionnaires used for evaluation of quality of life and / or patients who are illiterate.