Treatments for Prostate Cancer Spread to Bones

If prostate cancer spreads (metastasizes) to other parts of the body, it nearly always goes to the bones first. If the cancer has grown outside the prostate, a major goal of treatment is preventing or slowing the spread of the cancer to the bones. If the cancer has already reached the bones, controlling or relieving pain and other complications is also a very important part of treatment.

Dealing with bone metastasis

Bone metastasis can be painful and can cause other problems, such as fractures (breaks), spinal cord compression (when a tumor presses on the spinal cord), or high blood calcium levels, which can be dangerous or even life threatening.

Treatments such as hormone therapy, chemotherapy, targeted drugs, and immunotherapy may help with this, but other treatments specifically target bone metastasis and the problems it may cause.

Bisphosphonates

Bisphosphonates are drugs that work by slowing down bone cells called osteoclasts. These cells normally break down the hard mineral structure of bones to help keep them healthy. When prostate cancer spreads to the bones, osteoclasts can become overactive, which can cause problems. Bisphosphonates can be used:

• To help relieve pain and high calcium levels caused by cancer that has spread to the bones
• To help slow the growth of cancer that has spread to the bones and help delay or prevent fractures
• To help strengthen bones in men who are getting hormone therapy

Zoledronic acid (Zometa, other names) is a commonly used bisphosphonate for prostate cancer. This drug is given as an intravenous (IV) injection, usually once every 3 or 4 weeks. Men given this drug are advised to take a supplement containing calcium and vitamin D to prevent problems with low calcium levels.

Sometimes other bisphosphonates are used to treat prostate cancer that has spread to bone.

Side effects of bisphosphonates can include flu-like symptoms and bone or joint pain. These drugs can also cause kidney problems, so patients with poor kidney function might not be able to be treated with these medicines.

A rare but very serious side effect of these drugs is osteonecrosis of the jaw (ONJ). With this condition, part of the jawbone loses its blood supply and dies. This can lead to tooth loss and infections of the jawbone that are hard to treat. Some people develop ONJ when dental work is done during treatment. Men are often advised to have a dental checkup and have any tooth or jaw problems treated before they start taking a bisphosphonate. Maintaining good oral hygiene by flossing and brushing, making sure that dentures fit properly, and having regular dental checkups may also help prevent ONJ.

Denosumab

Denosumab (Xgeva, Prolia) is another drug that can help when prostate cancer spreads to the bones. Like bisphosphonates, denosumab also blocks osteoclasts, but it does so in a different way. This drug can be used:

• To help prevent or delay problems like fractures in men whose cancer has already spread to the bones. It may be helpful even if zoledronic acid is no longer working.
• To help strengthen bones in men who are getting hormone therapy

This drug is injected under the skin. It is typically given between once every 4 weeks to once every 6 months, depending on why it’s being used. Men given this drug are often advised to take a supplement containing calcium and vitamin D to prevent problems with low calcium levels.

Common side effects of denosumab include nausea, diarrhea, and feeling weak or tired. Like the bisphosphonates, denosumab can also cause ONJ, so doctors recommend taking the same precautions (such as having teeth and jaw problems treated before starting the drug).

Corticosteroids

Corticosteroid drugs (such as prednisone and dexamethasone) might also help relieve bone pain in some men. They also can help lower PSA levels.

These drugs are often already a part of treatment for prostate cancer that has spread, as they’re often given along with certain chemo or hormone therapy drugs.

External radiation therapy

Radiation therapy can help reduce bone pain, especially if the pain is limited to one or only a few areas of bone. Radiation can be aimed at tumors on the spine, which can help relieve pressure on the spinal cord in some cases, and prevent paralysis. In some centers this is done with stereotactic body radiation therapy (SBRT), which allows the treatment to be completed more quickly.

Radiation therapy may also help relieve other symptoms by shrinking tumors in other parts of the body.

Radiopharmaceuticals

Radiopharmaceuticals are drugs that contain radioactive elements. They are injected into a vein and settle in areas of damaged bones (like those containing cancer spread). Once there, they give off radiation that kills cancer cells.

These drugs can be used to treat prostate cancer that has spread to many bones. Unlike external beam radiation, these drugs can reach all the affected bones at the same time.

The radiopharmaceuticals that can be used to treat prostate cancer that has spread to the bones include:

• Radium-223 (Xofigo)
• Strontium-89 (Metastron)
• Samarium-153 (Quadramet)

All of these drugs can help relieve pain caused by bone metastases.

Radium-223 has also been shown to help men who have prostate cancer spread only to their bones (as opposed to spread to other organs such as the lungs) to live longer. For these men, radium-223 may be an early part of treatment.

The major side effect of these drugs is a decrease in blood cell counts, which could increase risks for infections or bleeding, especially if your counts are already low. Other side effects are also possible, so ask your doctor what you can expect.

Ablative treatments

These treatments focus extreme heat or cold on bone tumors to ablate (destroy) them. Ablative treatments might be an option if there are only a few tumors, especially if radiation isn’t helpful. One drawback with some ablative techniques is that they require a probe to be inserted into the tumor, which isn’t always possible with bone tumors.

Examples of ablative treatments include:

High-intensity focused ultrasound (HIFU): For this technique, a probe outside the body precisely focuses ultrasound waves on the tumor to heat and destroy the cancer cells.

Radiofrequency ablation (RFA): In this approach, a thin metal probe is inserted into the tumor. An electric current is then run through the probe, which heats the tip to destroy the cancer cells.

Cryoablation (cryotherapy): For this treatment, a thin, hollow metal probe is inserted into the tumor. Very cold gases are passed into the probe, which freezes the cancer cells. The tumor is then thawed, and the process is typically repeated.

Other ablative techniques now being studied include microwave ablation, laser ablation, and irreversible electroporation (IRE).

Surgery

Kyphoplasty is a minor surgery to stabilize a painful collapsed bone in a spine weakened by prostate cancer. During this procedure, a small incision is made in the middle of the back, and a balloon is placed into the weak spinal bone. The balloon is first filled with air and then a cement-like mixture (which will harden) to stabilize the bone and spine.

Pain medicines

When properly prescribed, pain medicines are very effective. Pain medicines work best when they’re taken on a regular schedule. They don’t work as well if they’re only used when the pain becomes severe.

If you have bone pain from prostate cancer, it’s very important that it’s treated. This can help you feel better and let you focus on the things that are most important to you. Don’t hesitate to discuss pain, other symptoms, or any quality-of-life concerns with your cancer care team. Pain and most other symptoms of prostate cancer can often be treated.

To learn more about pain, how to talk to your cancer care team about it, and the different ways to manage it, see Cancer Pain.