If prostate cancer spreads to other parts of the body, it nearly always goes to the bones first. Bone metastasis can be painful and can cause other problems, such as fractures (breaks) or high blood calcium levels, which can be dangerous or even life threatening.
If the cancer has grown outside the prostate, preventing or slowing the spread of the cancer to the bones is a major goal of treatment. If the cancer has already reached the bones, controlling or relieving pain and other complications is also a very important part of treatment.
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. Osteoclasts often become overactive when prostate cancer spreads to the bones, 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) is the most 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.
Some doctors use other bisphosphonates to treat prostate cancer that has spread to bone.
Bisphosphonates can have side effects, including flu-like symptoms and bone or joint pain. They 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 jaw bone loses its blood supply and dies. This can lead to tooth loss and infections of the jaw bone that are hard to treat. Some people develop ONJ when dental work is done during treatment. Many cancer doctors advise men 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 (Xgeva, Prolia) is another drug that can help when prostate cancer spreads to bone. Like the bisphosphonates, denosumab also blocks bone cells called 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 slow the spread of the cancer to the bones in men with no obvious cancer spread but with rising PSA levels despite hormone therapy
This drug is injected under the skin every 4 weeks. 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 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).
Some studies suggest that corticosteroid drugs (such as prednisone and dexamethasone) can help relieve bone pain in some men. They also can help lower PSA levels.
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. Radiation therapy may also help relieve other symptoms by shrinking tumors in other parts of the body.
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 spread to bone include:
- Strontium-89 (Metastron)
- Samarium-153 (Quadramet)
- Radium-223 (Xofigo)
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 have also been seen, so ask your doctor what you can expect.
When properly prescribed, pain medicines (ranging from over-the-counter ibuprofen or acetaminophen to stronger prescription medicines like morphine) are very effective. You may worry about addiction with pain medicines, but this is almost never a problem if these drugs are used as directed to treat cancer pain. Symptoms such as drowsiness and constipation are common but can usually be treated by changing the dose or by adding other medicines.
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. Several long-acting forms of opioids (prescription medicines such as morphine) are in pill form and only need be taken once or twice a day. There is even a long-acting patch that only needs to be applied every few days.
If you have bone pain from prostate cancer, it’s very important that it is treated effectively. 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 effectively. If the treatments listed above don’t help with symptoms, there are several other options.
Last Revised: 03/11/2016