Using Prolia for Bone Loss in People With Breast Cancer
Key takeaways:
Aromatase inhibitors (AIs) are a group of medications used to treat breast cancer in people who have gone through menopause, but they can cause bone loss and raise the risk of breaking a bone.
Prolia (denosumab) is a twice-yearly injection that’s FDA-approved to treat bone loss.
Prolia can cause low blood calcium levels, so your healthcare provider may recommend you take calcium and vitamin D supplements while receiving Prolia.
A healthy diet and certain exercises can help support overall bone health, but ask your healthcare provider if they’re safe and appropriate for you before making these changes.
Osteoporosis — a condition that happens when your bones lose their strength — affects about 10 million people in the U.S., with another 44 million people at risk of developing the condition. Having osteoporosis raises your risk of breaking a bone. For older adults, breaking a bone can lead to serious complications, including blood clots.
While osteoporosis most often happens to older adults, certain medications can raise your risk of developing this condition, regardless of your age. One class of medications that can cause bone loss is aromatase inhibitors (AIs), a common group of breast cancer medications used for people who have gone through menopause.
Because of this risk, healthcare providers may also prescribe medication to help prevent or treat this side effect for people taking AIs. Prolia (denosumab) is one of the bone-strengthening medications that your provider may discuss with you.
Below, we’ll discuss why AIs cause bone loss, how Prolia works to combat this side effect, and what to expect if your healthcare provider prescribes it for you.
What are aromatase inhibitors, and why do you take them for breast cancer?
AIs are a group of medications used to treat both early- and advanced-stage breast cancer in people who have gone through menopause. The following are the currently FDA-approved AIs:
Anastrozole (Arimidex)
Exemestane (Aromasin)
Letrozole (Femara)
AIs treat breast cancer by stopping an enzyme (protein) called aromatase from working. In people who have gone through menopause, aromatase helps the body turn androgens — hormones like testosterone — into estrogen. After menopause, a person’s internal reproductive organs no longer make estrogen, so the body primarily produces estrogen in this way.
There are many different kinds of breast cancer. Some forms of breast cancer — known as estrogen-receptor positive (ER+) breast cancer — use estrogen to grow. AIs help block the body’s source of estrogen, which cuts off the supply to breast cancer cells.
What side effects are associated with aromatase inhibitors?
Estrogen is important for multiple bodily functions. Besides reproductive health, this hormone also helps with maintaining cholesterol balance and protecting bone health. Because estrogen affects many areas of the body, many side effects of AIs are caused by a drop in estrogen levels.
Common side effects of AIs include:
Hot flashes
Weakness
Joint pain
Vaginal dryness
Pain during sex
Nausea
Trouble sleeping
AIs are also known to cause bone loss that can lead to osteoporosis. Since people who have gone through menopause already have a higher risk of osteoporosis than people who haven’t, this side effect is concerning. Osteoporosis raises your risk of breaking a bone. After breaking a bone — besides being painful — you may be more likely to depend on others, have symptoms of depression, and even have a higher risk of death.
Why does bone loss happen with aromatase inhibitors?
As mentioned, AIs block the body from creating estrogen. Estrogen helps the body create new bone and prevents the body from breaking down older bone. This keeps your bone mineral density (BMD) — a measure of the amount of calcium and other minerals in your bones — higher and your bones healthier.
Low estrogen levels make it harder for your body to make and protect bone cells properly. Since AIs lower your estrogen levels, this hormone isn’t as available to help keep your bones healthy.
How does Prolia work to treat bone loss in people taking aromatase inhibitors?
Prolia is a monoclonal antibody — an artificial protein that can target certain parts of the immune system — that binds to a receptor (chemical binding site) involved in bone breakdown. When activated, this receptor tells your body to start breaking down old bone cells.
Prolia stops this message from being communicated, helping your bone cells stick around for longer. So although AIs can prevent your body from making new bone cells, Prolia helps stop the bone cells you have from being destroyed.
Because it’s effective at preventing fractures in people taking AIs for breast cancer, Prolia is considered to be a first-choice option.
How long do you have to take Prolia?
Prolia is an injectable medication given by a healthcare professional under the skin in the upper arm, upper thigh, or stomach once every 6 months. It’s recommended that you use Prolia — or another medication called zoledronic acid (Reclast, Zometa) — the entire time you are taking AI medications. However, if your BMD remains low after finishing AI treatment, your healthcare provider may recommend you continue the medication post-treatment.
What side effects are associated with taking Prolia?
Like all medications, Prolia has risks and side effects. The most common side effects for people who have gone through menopause include:
Back pain
Pain in extremities, such as hands or feet
Muscle pain
High cholesterol
Bladder inflammation
One of the biggest risks with using Prolia is that it can cause low blood calcium levels. Because of this, you will need regular blood tests to measure your calcium levels before starting and while using this medication.
To help prevent low calcium, your healthcare provider may also recommend you take over-the-counter (OTC) calcium and vitamin D supplements while on Prolia. The manufacturers on Prolia recommend taking 1,000 mg of calcium and at least 400 IU of vitamin D per day. However, you should follow your healthcare provider’s instructions, as they may recommend a different dose for you.
Prolia has also been known to cause a rare but serious side effect called osteonecrosis of the jaw (ONJ). ONJ is a condition in which the bone cells of your jawbone start to die. Going for routine dental exams and following good dental hygiene practices while on Prolia will help keep your risk of ONJ low.
Is Prolia used for people with other types of cancer?
Prolia is also FDA-approved for other uses, such as preventing bone loss caused by some prostate cancer medications. However, this medication isn’t approved to directly treat cancer or its complications.
Xgeva is a higher dose of denosumab — the medication in Prolia. Unlike Prolia, Xgeva is FDA-approved for certain cancer-related complications. Xgeva is also given more frequently than Prolia — at least every 4 weeks compared to every 6 months.
Xgeva is FDA-approved for the following uses:
Prevention of bone-related problems caused by multiple myeloma or metastatic cancer (cancer that started as a solid tumor and then spread to other areas of the body) that has spread to the bones
Treatment of giant cell tumor of bone — a non-cancerous growth on bones — that can’t be removed with surgery
High blood calcium that is caused by cancer (called hypercalcemia of malignancy)
Are there any alternatives to treat or prevent bone loss?
As mentioned, another medication recommended to treat or prevent bone loss caused by AIs is zoledronic acid. However, this medication is not FDA-approved for this use, so it’s considered an off-label use. This medication is given once a year as an intravenous (IV) infusion into your vein.
If getting to a healthcare facility to receive Prolia or zoledronic acid is difficult, your healthcare provider may choose to prescribe an oral bisphosphonate medication, like alendronate (Fosamax) or ibandronate (Boniva). However, these medications are less effective than Prolia and zoledronic acid for this type of bone loss, so they’re less preferred.
There are other actions you can take to help prevent bone loss. If your healthcare provider hasn’t already recommended it, ask if you should be taking calcium and vitamin D supplements. These two nutrients are important in keeping your bones healthy. Be sure to ask how much of each you should be taking per day.
A healthy, balanced diet that includes fruits, vegetables, and protein are also important for bone health. There are multiple foods that are high in the vitamins and minerals your bones need to help stay healthy. Discuss this with your healthcare provider before making any dietary changes.
Lastly, certain exercises can be helpful in keeping your bones — and the muscles around them — strong. While you should always discuss exercise routines with a healthcare provider before starting them, they are generally recommended for many people with or at risk of developing osteoporosis.
The bottom line
AI medications are a common choice for treating breast cancer in people who have gone through menopause. However, these medications are known to cause bone loss that can lead to osteoporosis — a condition characterized by weak bones. This side effect raises your risk of broken bones.
To combat this complication of AIs, your healthcare provider may prescribe you Prolia. This twice-yearly injection is FDA-approved to help treat bone loss caused by these breast cancer medications.
While Prolia does carry risks and side effects of its own, it’s considered a first-choice option by experts to help prevent bone fractures in people taking AIs. If you’re taking an AI medication for breast cancer, ask your healthcare provider whether Prolia is right for you.
Why trust our experts?
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