An Observational Study of Adherence to Anastrozole in Early Breast Cancer Treatment

Inclusion Criteria: * Postmenopausal woman with early breast cancer who are prescribed with anastrozole as adjuvant endocrine therapy under the routine clinical practice. * Histologically or cytologically proven to be HR+(ER or PR +) * No other concomitant endocrine therapy such as estrogen therapy or selective estrogen receptor modulators * Provision of written informed consent Exclusion Criteria: * Recurrence of breast cancer * Known hypersensitivity to anastrozole or to any of its excipients * Any severe concomitant condition which makes it undesirable for the patient to participate in the trial or which would jeopardize adherence with the trial protocol: Amenorrhea\<12 months and a intact uterus; Previous inclusion in the present study; Participation in a other clinical study during the last 30 days· * Women who does not agreed to participate the program