How Do You Treat Bone Loss Caused by Hormone Therapy for Prostate Cancer?
Key takeaways:
Androgen deprivation therapy (ADT), also known as hormone therapy, is a common treatment for prostate cancer.
Bone loss is a possible side effect of ADT and can lead to osteoporosis or broken bones.
Prolia (denosumab) is the only FDA-approved medication for preventing ADT-related bone loss. But there are other off-label options that can be prescribed.
Prostate cancer affects about 1 in every 8 men in the U.S. There are multiple ways to treat prostate cancer. One common type of treatment is androgen deprivation therapy (ADT), also called hormone therapy.
Prostate cancer often uses the hormone testosterone to grow. So, the goal of hormone therapy is to lower testosterone levels in the body or block testosterone’s effects.
Among the many possible side effects of hormone therapy for prostate cancer are weakened bones. Testosterone plays an important role in keeping bones healthy for men. But when ADT lowers testosterone levels, it can lead to bone loss. In some cases, this can cause osteoporosis and increase your risk of broken bones (fractures). Thankfully, there are options to help manage this side effect.
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In this article, we’ll discuss the medications recommended to treat bone loss caused by hormone therapy for prostate cancer.
What FDA-approved treatments are available for bone loss caused by hormone therapy for prostate cancer?
Currently, only one medication is FDA-approved to treat bone loss from ADT: Prolia (denosumab). This twice-yearly injection is a monoclonal antibody, meaning it’s a lab-made protein that looks like a part of the immune system.
There’s a receptor (a chemical-binding site) in the body that plays a role in bone breakdown. When triggered, this receptor tells your body to break down old bone cells. Prolia attaches to a protein that activates this receptor. This action blocks this message and prevents the body from breaking down bone.
In studies, Prolia raised the bone mineral density (BMD) of study participants. BMD is a measurement of the amount of calcium and other minerals in your bones. It helps diagnose osteoporosis. The lower your BMD is, the more likely it is that you have osteoporosis.
In those same studies, Prolia also lowered the risk of spine fractures. As we’ll discuss next, experts aren’t sure if other medications have this benefit.
Can you use off-label medications to prevent bone loss related to hormone therapy?
Yes. There are other, off-label medications that can be prescribed for bone loss due to ADT. These medications belong to a class called bisphosphonates. Bisphosphonates attach to the surface of bones and prevent them from being broken down.
There are several bisphosphonates available. But the National Comprehensive Cancer Network (NCCN) recommends only two for ADT-related bone loss: alendronate (Fosamax) or zoledronic acid (Reclast). A healthcare provider could prescribe one of these instead of Prolia.
These two bisphosphonates can help prevent bone loss for people using hormone therapy. But it’s unclear whether they can help prevent broken bones. The studies for bisphosphonates didn’t have enough participants to determine this.
What are the side effects of using Prolia to prevent bone loss?
The most common side effects of Prolia for people with ADT-related bone loss are:
Joint pain
Back pain
Pain in the extremities (hands and feet)
Muscle pain
Less commonly, people using Prolia have reported developing cataracts. Cataracts occur when the lens of the eye becomes cloudy. They can cause blurry vision or vision loss and require surgery to be removed.
Prolia can also cause low blood calcium levels. Your healthcare provider will likely ask you to have regular blood tests done to watch for this. Because of this risk, it’s recommended to take a calcium and vitamin D supplement daily while you’re taking Prolia.
Very rarely, Prolia can cause a serious side effect called osteonecrosis of the jaw (ONJ). ONJ is a condition in which your jawbone starts to break down. Regular dental checkups and good dental hygiene at home can lower the risk of this side effect.
How long do you have to take Prolia for bone loss?
There isn’t a lot of long-term research available about any bone-strengthening medications for people with prostate cancer. It’s best to speak with your healthcare provider or cancer specialist about this. They’ll take your personal risk factors for osteoporosis and bone fractures into account when recommending how long to continue Prolia.
Who’s most at risk for bone loss caused by hormone therapy for prostate cancer?
Using hormone therapy for prostate cancer for any amount of time carries a risk of bone loss. And the longer you use hormone therapy, the more likely you are to experience bone loss.
Other factors that increase your risk for bone loss and osteoporosis include:
Age 70 years or older
Between 50 and 69 years old with other additional risk factors (e.g., smoking, excessive alcohol use)
Breaking a bone after age 50
Certain medical conditions (e.g., rheumatoid arthritis) that are linked with bone loss
Taking corticosteroid medications, such as prednisone, for 3 months or more
What risks are associated with using off-label medications to treat bone loss?
The biggest risk with using bisphosphonates instead of Prolia is that they may not be as effective. NCCN guidelines aren’t able to determine if bisphosphonates could prevent broken bones. Larger studies are needed to confirm this.
Prolia’s studies, on the other hand, did show that it could prevent fractures. Its ability to lower the risk of fractures is why Prolia is the only medication FDA approved for ADT-related bone loss.
But if you can’t take Prolia, alendronate or zoledronic acid are acceptable alternatives. Speak to your healthcare provider about which option is best for you. Keeping your bones healthy during hormone therapy is important.
What’s the outlook like for someone experiencing cancer-related bone loss?
The amount of bone loss and risk of fractures is unique for all people using ADT. It’s difficult to predict how severe this side effect may become. But if you develop osteoporosis, it’s not reversible.
It’s important to discuss a bone health plan with your cancer specialist. Besides medications and supplements, a plan could include dietary changes and certain exercises. There are many steps you can take to help keep your bones strong.
The bottom line
Bone loss is a possible side effect of hormone therapies used to treat prostate cancer. The longer you use hormone therapy, the higher your risk of bone loss becomes. This puts you at risk for osteoporosis and breaking bones.
Prolia is the only FDA-approved medication to treat bone loss from ADT. But if you can’t take Prolia, there are other options available. These alternatives are prescribed off-label, but they are recommended by experts. Be sure to discuss the best ways to combat bone loss with your healthcare provider.
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References
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