Key points
- Some endocrine therapies, such as aromatase inhibitors, can cause bone density loss.
- Bone mineral density monitoring is recommended for patients considering endocrine therapy, including DEXA scans as per recommended guidelines.
- Bisphosphonates are used to help minimise bone loss, especially for patients diagnosed with advanced breast cancer.
- In New Zealand, zoledronic acid and risedronate (Actonel) are the two publicly funded bisphosphonates.
Bone health on endocrine therapy
Adjuvant endocrine therapies, like aromatase inhibitors, are associated with a loss of bone density. This increases the risk of bone-related side effects, including increased risk of fracture.
Patients being considered for endocrine therapy should undergo bone mineral density monitoring, following a baseline DEXA scan of the spine and hip.
The Management of Early Breast Cancer - Evidence-based Best Practice Guidelines outlines the following guidelines for monitoring of bone health:
- Post-menopausal women and women with cancer treatment-induced premature menopause taking aromatase inhibitors should have bone density monitored every two years after a baseline DEXA scan.
- Frequency of monitoring is dependent upon the individual. If baseline T-score is >-1.0 further monitoring may not be necessary.
- Talk to patient’s about bone density monitoring, and adequate calcium intake, if the patient has a strong family history of osteoporosis or a personal history of a fracture after a minor fall.
Bisphosphonates (bone-specific therapy)
Bisphosphonates are a group of medications that have been commonly used to combat bone loss. They are often used in advanced breast cancer care to reduce osteodynia and improve patients’ quality of life. However, they have also been used as adjuvant treatment for post-menopausal women (including those who are having their ovarian function suppressed) with early breast cancer, to prevent treatment-induced osteoporosis and to reduce the risk of developing bone metastases.
The Management of Early Breast Cancer - Evidence-based Best Practice Guidelines recommends the following groups be prescribed bisphosphonates:
- Women with cancer treatment-induced premature menopause and on adjuvant endocrine therapy that enhances loss of bone density.
- Women who are on osteoporotic and on adjuvant endocrine therapy that enhances loss of bone density.
- Women in the above groups who have further risk factors, including prior non-traumatic fracture, aged over 65 years, family history, tobacco use and low body weight.
In New Zealand, Zoledronic acid and Risedronate (Actonel) are the two bisphosphonates that are publicly funded,
Zoledronic acid is administered via IV infusion. In breast cancer treatment, it is given every six months for two years. It is also known as Aclasta and Zometa.
Risedronate (Actonel) is a tablet taken orally once a week. For more information, see the Medsafe data sheet.
