From the Guidelines
Aromatase inhibitors can be used in patients with osteoporosis, but require close monitoring and additional management strategies to mitigate the risk of further bone loss. The direct recommendation is to:
- Assess bone mineral density before starting treatment
- Prescribe calcium (1000-1200 mg daily) and vitamin D (800-1000 IU daily) supplements
- Consider adding a bisphosphonate (e.g., alendronate 70 mg weekly) for bone protection
- Monitor bone density annually with DEXA scans
- Evaluate for fracture risk using tools like FRAX Aromatase inhibitors (e.g., anastrozole, letrozole, exemestane) work by lowering estrogen levels, which can accelerate bone loss, as noted in the american cancer society/american society of clinical oncology breast cancer survivorship care guideline 1. However, their benefits in treating hormone-responsive breast cancer often outweigh this risk. The key is to proactively manage bone health. For patients with severe osteoporosis or multiple risk factors, alternative endocrine therapies like tamoxifen may be preferable, as it has bone-protective effects, although this may not be suitable for all patients due to the potential for reduced efficacy when combined with aromatase inhibitors 1. Regular weight-bearing exercise and smoking cessation should also be encouraged to support bone health while on aromatase inhibitors. It is essential to weigh the benefits of aromatase inhibitors against the potential risks, particularly in patients with pre-existing osteoporosis, and to consider the findings of recent studies, such as the NCCN task force report on bone health in cancer care 1, which highlights the importance of managing bone health in patients receiving aromatase inhibitors.
From the FDA Drug Label
WARNINGS AND PRECAUTIONS • Reductions in bone mineral density (BMD) over time are seen with exemestane use (5.1)
The use of aromatase inhibitors (AIs) like exemestane may be concerning in patients with osteoporosis due to the potential for further reductions in bone mineral density (BMD).
- Key consideration: Patients with osteoporosis may be at increased risk of worsening bone health with AI use.
- Clinical decision: Aromatase inhibitors should be used with caution in patients with osteoporosis, and alternative treatments may be considered. 2
From the Research
Aromatase Inhibitors and Osteoporosis
- Aromatase inhibitors (AIs) are associated with significantly more osteoporotic fractures and greater bone mineral loss 3, 4.
- The use of AIs can lead to accelerated bone loss and an increased risk of fracture, particularly in osteopaenic women 4.
- Current guidelines advocate for bone mineral density (BMD) measurement in all patients on AIs, with selective use of antiresorptive therapy in osteoporotic women (T-score < -2.5) 3, 4.
Management of Osteoporosis in Patients on AIs
- Bisphosphonates, such as alendronate, risedronate, and zoledronic acid, have efficacy in preventing postmenopausal osteoporosis and cancer treatment-related bone loss 3.
- Emerging evidence supports the concomitant use of bisphosphonates in all women on AIs to prevent fracture and breast cancer recurrence 4.
- Modifiable lifestyle behaviors, including adequate calcium and vitamin D intake, weight-bearing exercise, and smoking cessation, should be addressed in patients on AIs 3.
Screening and Treatment of Osteoporosis
- Screening for osteoporosis is essential in patients on AIs, with a baseline DEXA scan and yearly follow-up scans recommended 5.
- Appropriate management of osteoporosis in patients on AIs includes calcium and vitamin D therapy, and consideration of bisphosphonate therapy in patients with osteopenia or osteoporosis 5, 6.
- Antiresorptive medications, such as bisphosphonates and denosumab, can lower the risk of bone loss from AIs and are increasingly used as adjuvant treatment in breast cancer 6.