Impact of Chemotherapy Followed by Aromatase Inhibitors on Bone Health of Women With ER-positive Early Breast Cancer

Inclusion Criteria:

* Provision of informed consent.
* Age ≥ 40 years.
* Female patients with ER-positive early breast cancer, who receive therapy with a third generation AI either as first line hormonal treatment or as maintenance therapy after first-line anthracycline- and/or taxane-based chemotherapy for a period no longer than 1 month (4 weeks) prior to inclusion in the present study.
* Women who have been rendered postmenopausal prior to chemotherapy commencement and at least 12 months from last menstrual period. For subjects who are amenorrheic for \< 12 months (including patients who underwent hysterectomy, or received estrogen replacement therapy (ERT)/ hormone replacement therapy (HRT), they must have serum follicle stimulating hormone (FSH) ≥50 IU/L before the commencement of AI therapy.
* Patients with available data on lumbar spine and total hip bone mineral density (BMD) prior to chemotherapy initiation as well as before the commencement of AI therapy.

Exclusion Criteria:

* Prior administration of other endocrine therapy including tamoxifen.
* Chemotherapy-induced menopause.
* Evidence of diseases known to interfere with bone metabolism, such as hyperparathyroidism, hyperthyroidism, osteomalacia, chronic liver disease, renal failure, hypercortisolism, malabsorption, and immobilization.
* Evidence of bone metastasis or evidence of abnormal clinical laboratory parameters that are assessed as clinically significant by the investigator.
* Involvement in the planning and conduct of the study.
* Participation in other clinical study within a period of 3 months prior to any study related procedures.
* Patients with normal bone density or mild osteopenia (T score \>= -2 in any site) under treatment with oral or intravenous bisphosphonates. Vitamin D and calcium supplements are allowed.
* Patients with severe osteopenia or osteoporosis (T score \<= -2 in any site) under treatment with intravenous bisphosphonates. Oral bisphosphonates, Vitamin D and calcium supplements are allowed.
* Patients under treatment with oral or intravenous bisphosphonates before chemotherapy commencement.
* Patients that stopped hormone-replacement therapy (HRT) less than 3 months before chemotherapy commencement.
* Patients that received neo-adjuvant treatment.