Bone Health After Cancer
How do bones work?
Bones give your body structure and support, and help store nutrients. Your body has a way of breaking down old or damaged bones and forming new ones to keep your bones strong. Osteoclasts are cells that break down old bone, and osteoblasts are cells that form new bone. The hormones estrogen, testosterone, and parathyroid hormone help this process of breaking down and forming new bone.
In osteoporosis, more bone is being destroyed than is being formed, causing weak bones.
What is osteoporosis?
If you had cancer treatment in the past or are currently having it, it can raise your risk of osteoporosis. Osteoporosis and osteopenia (the precursor to osteoporosis) are medical terms for decreases in bone density or a "thinning" or weakening of the bones. This raises the risk of fracture (breakage) of your bones. It most often affects the hips, spine, and wrists, and is the cause of 2 million broken bones a year in the United States. Ask your provider about your risk for osteoporosis. There are screening tools available and certain ways to prevent it.
Who is at risk for bone issues?
- Women who have premature (early) menopause or less estrogen production due to cancer therapy (such as hormonal therapy, like aromatase inhibitors or leuprolide, or menopause caused by surgery, chemotherapy, or radiation). Tamoxifen (Nolvadex®) increases the risk of osteoporosis in premenopausal women, but in menopausal women it can increase bone density, lessening the chance of osteoporosis.
- Men who have decreased testosterone production. This is a common concern for men treated with androgen deprivation therapy (ADT) or orchiectomy (surgery to remove testicles) for prostate cancer.
- Treatment with some chemotherapy medications, radiation to the brain or weight-bearing bones (spine, hips, legs), or allogeneic stem cell or bone marrow transplant.
- Survivors of childhood cancers.
- Long-term use of corticosteroids like dexamethasone (Decadron®) and prednisone (Sterapred®, Prednisone Intensol), greater than 5 mg per day for 2 months or more.
- If you have had your stomach surgically removed (gastrectomy).
There are other risk factors that are not specific to having cancer, such as smoking, drinking excessive alcohol, leading an inactive lifestyle, being petite and thin, having a diet low in calcium and vitamin D, being an older age, and missing menstrual periods. Osteoporosis is more common in women. Out of 10 million people, 8 million women have osteoporosis. It is also more common in people with a family history, Caucasians, and people of Asian or Latino descent, although all races have some risk. You can learn more about other risk factors by visiting the Bone Health and Osteoporosis Foundation.
How is osteoporosis found?
Screening for osteoporosis is done with a bone mineral density (BMD) test. A DEXA scan is the most common test. The United States Preventive Services Task Force recommends that women have the test at age 65 and older. Younger postmenopausal women with one or more risk factors should be screened. Since osteoporosis is less common in men, some guidelines recommend screening at age 70, while others recommend screening if the person has risk factors. Ask your healthcare provider if you should be screened. The test is also used to check the bone health of people with osteopenia or osteoporosis.
Experts recommend screening for all patients with cancer who are at increased risk because of their age or the treatments they received. Cancer survivors should talk about their specific risks and need for screening with their healthcare team. Risk can be evaluated using the FRAX® tool, which was developed by the World Health Organization (WHO) to look at the risk of fracture in people.
Dietary Tips
Calcium
Our bodies cannot produce calcium, so we must be sure to get enough in our diet to support healthy bones. You should aim to get 1000 to 1200 mg of calcium per day. It is best to get calcium in a balanced diet, including 4 to 8 servings of calcium-rich foods a day.
Dairy foods, like milk, yogurt, and cheese are highest in calcium. Canned fish (sardines and salmon with bones) and dark, green vegetables, such as broccoli, kale, and collard greens have calcium as well. Some foods are fortified with calcium but read the labels to get an idea of just how much they have. Calcium-fortified orange juice is a good source.
Spinach and rhubarb have calcium but also large amounts of oxalate and phytate, which prevent the body from absorbing (taking in) their calcium. However, they do not interfere with the absorption (taking up) of calcium from other foods. Other good sources of calcium include almonds, sunflower seeds, apricots, and figs. A dietitian can help you choose calcium-rich foods.
If you cannot take in the recommended amount of calcium in foods, take calcium supplements. Your body does not absorb calcium supplements well, so spread the dose out by taking 1 tablet multiple times a day. If you take Synthroid (thyroid hormone), separate it from calcium doses by at least 4 hours.
Vitamin D
Vitamin D is often called the "sunshine vitamin" because our skin converts ultraviolet rays from the sun into vitamin D. In general, 10 to 15 minutes of sun exposure on the hands, arms, and face creates the needed amount. However, it is difficult to measure how much vitamin D you are getting by this method, and the amount can vary by season or location. Avoiding the sun and using sunscreen limits how much UV exposure we get.
Very few foods contain vitamin D naturally; these include certain fish (salmon, tuna, mackerel) and fish liver oils, while egg yolks and beef liver contain small amounts. Many foods are fortified with vitamin D. Read the nutrition labels to know how much. Milk is often fortified with vitamin D, but keep in mind that foods made with milk (cheese, ice cream) are not.
Vitamin D is available in two forms, D2 and D3. Supplements often contain D3. Research has found that both are beneficial for bone health. A cup of fortified milk contains about 100 international units (IU) of vitamin D. A multivitamin contains 400 IU and some calcium supplements also include vitamin D. You should aim for 800-1000 IU per day. Your care provider may check your Vitamin D blood levels to see if you should take a supplement.
Reading Food Labels
Most foods have a Nutrition Facts or “food label” on the package. This label shows you what the nutritional facts are of the food. It can be hard to understand. The Food and Drug Administration (FDA) has approved a new "Nutrition Facts" label on food products that is easier to read. Food manufacturers are just starting to use this new label, so you may see the old labels still being used. On the old label, the content of calcium was listed as a percentage of the recommended daily amount (RDA or Daily Value). The new labels require manufacturers to list the actual amount of calcium, vitamin D, iron, and potassium, in addition to the Daily Value of these foods. This change will make it easier to determine how much calcium and vitamin D you are getting in packaged foods.
Medical Therapy
If you have osteoporosis or osteopenia, your healthcare team may recommend medications to prevent it from getting worse. Antiresorptive medications are often used and they work by slowing the rate of bone breakdown. While breakdown is slowed, the forming of bone occurs at the same speed, which may help bone density to improve. Antiresorptive medications include bisphosphonates such as alendronate, and zoledronic acid (Zometa®, Reclast®), etc. and raloxifene (Evista®), which is a selective estrogen receptor modifier or SERM, and calcitonin. PTH (teriparatide) is a type of parathyroid hormone that increases the rate of bone formation, helping strengthen your bones, but is not used as much because of its side effects. If you are taking a bisphosphonate, be sure to talk to your care provider if you have dental work planned, as you may need to stop this medication for a short time.
Each of the medications has some risk of side effects and may not work for every patient. Talk about your medical options for treating osteoporosis with your healthcare team.
Resources
Bone Health and Osteoporosis Foundation
International Osteoporosis Foundation (IOF)
WHO FRAX® tool (for estimating the risk of developing a bone fracture)
Resources about calcium and vitamin D and diet: