Maintaining Bone Integrity Throughout Breast Cancer Therapy
Breast cancer treatments can have a significant impact on bone health, particularly through the use of aromatase inhibitors, chemotherapy, and bone metastases.
Aromatase inhibitors (AIs), used as adjuvant endocrine therapy for hormone-sensitive breast cancer in postmenopausal women, are the most strongly linked to bone loss. These drugs reduce estrogen levels, which normally helps maintain bone density, leading to a higher risk of bone loss and fragility fractures. Postmenopausal women using AIs face a 2 to 4 times higher risk of bone loss and fractures compared to typical menopausal bone loss. This includes nearly double the risk of vertebral (spinal) fractures and increased risks of hip and non-vertebral fractures.
Chemotherapy can also worsen bone health by directly damaging osteoblasts, the cells responsible for new bone formation, contributing to weakened bones and osteoporosis.
Breast cancer that spreads to the bones (bone metastases) disrupts the normal bone remodeling process, often causing increased bone breakdown. This can lead to bone pain, fractures, spinal cord compression, and hypercalcemia (high blood calcium). Bone metastases themselves are serious complications affecting bone integrity independently of the drugs used.
Tamoxifen does not generally cause bone loss in postmenopausal women; in fact, it may have a protective effect, though it poses fracture risks in premenopausal women.
Other factors such as age, nutrition, body mass, family history of osteoporosis, physical activity, and corticosteroid use can influence the risk of treatment-related bone loss.
Managing AI-associated bone loss includes early assessment and use of bone-protective treatments like denosumab (Prolia) and bisphosphonates, which reduce fracture risk and may even improve breast cancer outcomes.
To maintain bone health during breast cancer therapy, it is essential to maintain a balanced diet rich in calcium, protein, magnesium, and vitamin D. Sources of calcium include dairy products, fortified foods, almonds, and dark green leafy vegetables. Protein can be obtained from lean meats, beans, nuts, tofu, and dairy products. Magnesium sources include spinach, avocados, bananas, dark chocolate, certain nuts and seeds. For extra vitamin D, people can eat oily fish, fortified foods, eggs, and mushrooms. Sunlight exposure on the skin twice per week or vitamin D supplements may be necessary to meet daily requirements.
Engaging in weight-bearing exercises for 30 minutes daily can also help stimulate new bone tissue and increase bone strength. Examples include walking, stair climbing, dancing, and weightlifting.
People who are at risk of fractures may need to keep taking osteoporosis medications after cancer treatment, as advised by a doctor.
Quitting smoking can reduce the impact of cancer treatment on bone health as it limits calcium absorption, slows the formation of bone-forming cells, decreases the protective effect of estrogen, and reduces blood supply to the bones. Radiation therapy increases the risk of bone loss and fractures.
In summary, effective monitoring and preventative treatment are essential for preserving bone health during breast cancer therapy. Understanding the impact of various treatments and taking proactive steps to maintain bone health can help improve the overall outcomes for breast cancer patients.
References: [1] Bone Health and Breast Cancer: Untangling the Web of Interactions. Cancer Treatment Reviews. 2017. [2] Bone Metastases. Breastcancer.org. 2021. [3] Bone Health and Breast Cancer: Prevention and Treatment. National Comprehensive Cancer Network. 2021. [4] Chemotherapy and Bone Health. Breastcancer.org. 2021. [5] Bone Health in Breast Cancer Survivors. American Cancer Society. 2021.
