Breast cancer

Women newly diagnosed with breast cancer can have unrecognised abnormalities of bone and mineral metabolism such as vitamin D deficiency, osteopenia, osteoporosis and primary hyperparathyroidism.

Aromatase inhibitors are often used to treat estrogen receptor–positive breast cancer. Women treated with an aromatase inhibitor require a baseline bone mineral density (BMD) measurement before starting treatment, because aromatase inhibitors cause a rapid and profound decline in serum estradiol concentration, resulting in rapid bone loss and fractures. A bisphosphonate or denosumab should be considered in women with any of the below:

• prevalent or incident clinical or morphometric fractures
• reduced BMD (T-score lower than –2 at the hip or spine)
• annual bone loss of 5% or more.

Tamoxifen treatment for breast cancer usually stabilises or increases BMD in postmenopausal women, but causes bone loss in premenopausal women.

Ensure the patient’s calcium intake is sufficient and they are vitamin D replete, and provide advice about lifestyle measures to prevent minimal-trauma fracture.

More detailed information about the management of bone health in women with estrogen receptor–positive breast cancer can be found in the joint position statement of the Endocrine Society of Australia, the Australian and New Zealand Bone and Mineral Society, the Australasian Menopause Society, and the Clinical Oncology Society of Australia¹.