Bone loss

Bone tissue grows throughout your life. To keep bones strong and healthy, special cells break down and rebuild bones. When more bone is rebuilt than is broken down, bones become dense, hard, and strong.

Bone loss happens when more bone cells break down than are rebuilt. That causes bones to weaken and become more likely to fracture or break.

All people experience bone loss as they age. Having breast cancer does not cause bone loss but some common treatments can increase risk. Even with healthy bones, it’s important to do what you can to support your bone health during and after breast cancer treatment.

Symptoms of bone loss

Early bone loss, called osteopenia, has no symptoms or pain. It's possible not to know you have serious bone loss, called osteoporosis, until you break a bone. Some people with osteoporosis have back pain or lose height, or their posture may become stooped. The more bone loss, the greater the risk for bone breaks.

A bone mineral density test, or DEXA scan, detects both osteopenia and osteoporosis. A DEXA scan is a different test than a bone scan, which might be given as part of testing for a breast cancer diagnosis or to investigate the source of bone pain.

Causes of bone loss

Breast cancer treatments that affect the way the body creates or uses estrogen increases the risk for or speeds up bone loss. These treatments are:

• Chemotherapy. Can cause early menopause or affect menstrual periods in any type of breast cancer.
  • If your period comes back in less than 6 months after you finish treatment, it's possible to reverse bone loss with lifestyle changes or medicines. Sometimes bones recover on their own.
• Hormonal therapy. Given to lower recurrence risk in hormone receptor-positive breast cancer. Aromatase inhibitors are associated with bone loss.
• Ovarian ablation and ovarian suppression for hormone receptor-positive breast cancer. Surgery, also called oophorectomy, removes the ovaries. Suppression medicines prevent ovaries from making estrogen.
  • Removing estrogen from your body mimics menopausal changes and puts you at risk for bone loss.

Some other key factors influence the chances of bone loss:

• Age. Most of our bone strength and health is built before age 30.
• Menopause. Estrogen helps bones rebuild. After menopause, estrogen levels go down, so postmenopausal women often have bone loss, regardless of cancer status.
• Sex. Females are more likely than males to develop osteoporosis.
• Exercise. Lack of exercise keeps bones from rebuilding well.
• Diet. Not getting enough calcium and vitamin D from foods or supplements.
• Lifestyle. Smoking, drinking too much alcohol, or taking illegal drugs all cause bone loss.
• Ethnicity. Osteoporosis risk is highest among white women and women of Pacific and Asian Islanders.
• Stature. People who are thin and have a small frame are at higher risk.

Other high risk factors for bone loss are:

• Too little or too much calcium in the body
• A family history of osteoporosis
• Not having had period for a long time
• You have or had an eating disorder
• Certain other medical conditions or certain medicines

Bone loss & metastatic breast cancer

With metastatic breast cancer, you may have extra worries about bone loss, which can result from cancer treatment itself, the spread of breast cancer to the bones, or both.

Metastatic breast cancer in the bone is called bone metastases. It's possible to learn about a bone metastasis from new bone pain or a fracture to the bone. An X-ray would show the cancer.

Common treatments used to address bone problems in metastatic breast cancer are:

• Bisphosphonates, such as zoledronic acid (Reclast, Zometa) and pamidronate (Aredia). These medications strengthen and protect bones. Bisphosphonates can lower levels of calcium in the blood, called hypercalcemia, if they are too high due to a tumor's effect on the bone, the tumor itself, or as a side effect of treatment.
• Targeted therapies, such as denosumab (Prolia, Xgeva, and biosimilar Jubbonti), that lower the risk of breaks and fractures.
• Supplemental calcium and vitamin D to support bisphosphonates and targeted therapies.
• Radiation therapy to strengthen bones.
• Surgery to stabilize a weak bone with a rod.

Avoiding & managing bone loss

A healthy lifestyle can help protect bones and make them stronger, even with bone loss. Here are some common strategies.

Exercise & physical activity

Regular exercise or regular physical activity helps bones become healthy and strong. The movement and muscle strength you gain from exercise helps maintain bones and repair weakened ones. Include weight-bearing exercises and strength training such as:

• Brisk walking
• Yoga
• Stair climbing
• Dancing or low-impact aerobics
• Racquet sports
• Gardening
• Using resistance bands or free weights
• Swimming

Talk to your doctor before trying a new exercise or starting a new exercise routine, or get a referral to a specialist. Learn more on our Exercise page and discover LBBC's exclusive BeACTive exercise series for those affected by breast cancer.

Diet

Eating a nutritious diet is also essential. Calcium and vitamin D are vital to maintain and rebuild bones. Some tips to improve your diet:

• Get more calcium by eating yogurt, low-fat milk, and other dairy products, fish, dark green leafy vegetables, and foods with added calcium.
• Eat foods with vitamin D. It helps the body absorb calcium. Vitamin D is found in oily fish, cheese, and fortified milk and cereal.
• Limit food and drink with caffeine. It may affect calcium levels.
• Talk with your doctor about whether you should be taking calcium and vitamin D supplements.

Medicine

When lifestyle changes aren’t enough to treat bone loss, some medications can be taken to maintain and strengthen bone:

• Bisphosphonates
  • Pills available are alendronate sodium (Fosamax), risedronate sodium (Actonel), and ibandronate sodium (Boniva)
  • By vein, zoledronic acid (Reclast, Zometa)
• Raloxifene (Evista), a pill that prevents and treats osteoporosis in postmenopausal women.
• Denosumab (Prolia, Xgeva), a type of medicine called a RANK ligand inhibitor that helps to grow bone mass in women at risk for fractures because of AI treatment. It is given by injection once every 6 months.
• Calcitonin nasal spray that is derived from salmon and helps make bone in postmenopausal women with osteoporosis.
• Tamoxifen, a standard treatment for premenopausal women, may help prevent bone loss after menopause.

Bisphosphonates and denosumab can cause a rare side effect of exposed bone in the jaw that does not heal, called osteonecrosis of the jaw or ONJ. The risk is higher in metastatic breast cancer to the bone because bisphosphonates may be used for a long time as part of breast cancer treatment. With denosumab, the risk increases the longer it's taken. See the dentist before starting bisphosphonate or denosumab, and talk to your oncology team before having invasive dental procedures such as tooth extractions.

Bisphosphonates can cause kidney problems. Your doctor should explore the pros and cons of these medicines with you before prescribing, as well as what follow-up monitoring may be needed.

Other general tips to help keep bones strong:

• Get help to stop smoking
• Avoid drinking too much alcohol
• Avoid illegal drugs