The aim of this study is to determine the effect of aromatase inhibitors therapy on bone mineral density and compare it to the effects of tamoxifen and no hormonal therapy.

Inclusion Criteria:

• Women aged 55-65 years, diagnosed with invasive early breast cancer: - Surgery, chemo- and/or radiotherapy concluded less than 6 months ago
• Women with hormone-independent breast cancer: - Surgery, chemo- and/or radiotherapy concluded before 24-36 months or 54-66 months
• Women with hormone-dependent breast cancer:- Adjuvant therapy with tamoxifen initiated before 24-36 and 54-66 months or - Adjuvant therapy with aromatase inhibitor initiated before 24-36 and 54-66 months or - Switch from tamoxifen to aromatase inhibitor initiated before 24-36 months

Exclusion Criteria:

• Women receiving active treatment for osteoporosis
• Women with any evidence of breast cancer recurrence

Institute of Oncology