Understanding Bone Metastasis
This section describes the types of systemic treatments used for patients with cancers that have spread to bones. These treatments can reach cancer cells anywhere in the body.
Of course, cancers can also spread to other parts of the body. For more detailed information about treating a certain type of metastatic cancer, please see our information on that type of cancer.
Some systemic treatments, such as chemotherapy, hormone therapy, and immunotherapy, are used to treat cancer cells anywhere in the body. These treatments are not aimed specifically at bone metastases, but they often help treat them. Other systemic treatments, such as radiopharmaceuticals and bisphosphonates, are aimed more specifically at cancer that has reached the bones. Sometimes both of these types of treatments are used at the same time.
Chemotherapy (chemo) uses anti-cancer drugs that are usually injected into a vein or taken by mouth. These drugs enter the bloodstream and can reach cancer that has spread. Chemo is used as the main treatment for many types of metastatic cancer. Chemo is often able to shrink tumors, which can reduce pain and help you feel better, although it does not usually make them go away completely. It is sometimes used with local treatments such as radiation.
Chemo drugs kill cancer cells but also damage some normal cells, which causes some side effects. Side effects depend on the type of drugs, the amount taken, and the length of treatment. Some common chemo side effects include:
- Nausea and vomiting
- Loss of appetite
- Loss of hair
- Mouth sores
Chemotherapy can also damage the blood-producing cells of your bone marrow, which may lead to low blood cell counts. This can cause:
- Increased chance of infection (caused by a shortage of white blood cells)
- Problems with bleeding or bruising (caused by a shortage of blood platelets)
- Feeling weak or fatigued (caused by low red blood cell counts, called anemia)
Most side effects go away once treatment is stopped. Your doctor can help you prevent or control many of the side effects of chemotherapy. For example, drugs can often prevent or reduce nausea and vomiting. To learn more about chemo, please see Understanding Chemotherapy: A Guide for Patients and Families.
Hormones in the body drive the growth of some common cancers. Estrogen, a hormone made by the ovaries, promotes growth of some breast cancers. Likewise, androgens (such as testosterone, which is made by the testicles) promote growth of most prostate cancers. One of the main ways to treat breast and prostate cancers is to stop these hormones from affecting the cancer cells. There are several types of hormone-blocking treatments.
One hormone treatment strategy is to surgically remove the organs that make the hormones. For a woman with breast cancer, removing the ovaries lowers estrogen levels. Men with prostate cancer can be treated by removing the testicles to lower testosterone levels.
More often, drugs are given to keep the hormones from being made. This is a common approach to hormone therapy for prostate cancer. Men can be given drugs such as luteinizing hormone-releasing hormone (LHRH) agonists or antagonists, which block testosterone production. The same drugs can be given to women with breast cancer to stop the ovaries from making estrogen. The ovaries no longer make hormones after menopause, but a small amount of estrogen is still made in fat tissue. Drugs called aromatase inhibitors stop this estrogen from being formed.
Another approach is to keep the hormones from affecting the cancer cells. For example, men with prostate cancer can be given anti-androgens, which block the hormones’ effects on cancer cells. For women with breast cancer, anti-estrogens like tamoxifen block the effects of estrogen on breast cancers.
Side effects of hormone treatments depend on the type of treatment used. The most common side effect for many of these treatments is hot flashes. Hormone treatment for prostate cancer can lead to anemia, weight gain, loss of sex drive, and other effects. Tamoxifen use increases the risk of blood clots and uterine cancer and can also cause other problems.
Immunotherapy is a systemic therapy that boosts the body's immune system or uses man-made versions of immune system proteins to kill cancer cells. Several types of immunotherapy are used to treat patients with metastatic cancer, including cytokines, monoclonal antibodies, and tumor vaccines. These treatments are discussed in our document called Immunotherapy.
Radiopharmaceuticals are a group of drugs that have radioactive elements. These drugs are injected into a vein and settle in areas of bone that contain cancer. The radiation they give off kills the cancer cells and relieves some of the pain caused by bone metastases. Some of the radiopharmaceuticals used most often are strontium-89 (Metastron®) and samarium-153 (Quadramet®). Other radiopharmaceuticals, such as radium-223, rhenium-186, rhenium-188, and tin-117 are also being studied.
If cancer has spread to many bones, radiopharmaceuticals work better than trying to aim external beam radiation at each affected bone. In some cases, radiopharmaceuticals may be combined with external beam radiation aimed at the most painful bone metastases (see “Radiation therapy” in the “Local treatments” section.)
Radiopharmaceuticals are given in a single dose. This single treatment can often reduce the pain for several months. Re-treatment is possible when the pain returns, although the pain may not be reduced for as long as it was with the first treatment.
These drugs work best when the metastases are blastic, meaning the cancer has stimulated certain bone cells (osteoblasts) to form new areas of bone. These areas look dense (white) on x-rays (as opposed to osteolytic lesions, which look like dark areas or holes in the bones). Blastic metastases happen most often in prostate cancer that has spread to bone. They are found less often in breast cancers and are uncommon in most other cancers.
The major side effect of this treatment is lower blood cell counts (mainly white cells and platelets), which could put you at increased risk for infections or bleeding. This is more of a problem if your counts are already low before treatment. Another possible side effect is a so-called "flare reaction," in which the pain gets worse for a short time before it gets better.
Bisphosphonates are a group of drugs that are useful in treating patients with cancer that has spread to their bones. These drugs work by slowing down the action of bone cells called osteoclasts. These cells normally dissolve small bits of bones to help remodel them and keep them strong. But osteoclasts are often overactive when cancer spreads to the bones, which can cause problems.
Bisphosphonates can help with cancer that has spread to the bones by:
- Reducing bone pain
- Slowing down bone damage caused by the cancer
- Reducing high blood calcium levels (hypercalcemia)
- Lowering the risk of broken bones
Bisphosphonates tend to work better when x-rays show the metastatic cancer is making the bone thinner and weaker (lytic metastases). They don't work as well for treating blastic metastases, where the bones become thicker.
Some bisphosphonates are taken by mouth, but most of the bisphosphonates used as treatment for bone metastasis are given by vein (IV), usually every 3 to 4 weeks. The most commonly used drugs are zoledronate (zoledronic acid or Zometa®) and pamidronate (Aredia®). Zoledronate can be infused more quickly and may reduce the risk of fracture somewhat better than pamidronate. Pamidronate seems to be less likely to cause osteonecrosis of the jaw, a rare but serious side effect (discussed below). People given these drugs are usually advised to take a supplement containing calcium and vitamin D to prevent problems with low calcium levels.
The most common side effects of bisphosphonates are fatigue, fever, nausea, vomiting, anemia (a low red blood cell count), and bone or joint pain. But other drugs or the cancer itself also may cause many of these effects, too. These drugs can lower calcium levels, so they can't be given to someone whose calcium levels are already low. People with poor kidney function may not be able to take a bisphosphonate.
A rare but very serious side effect of bisphosphonates is osteonecrosis of the jaw (ONJ). In this condition, part of the jaw bone loses its blood supply and dies. This can lead to tooth loss and infections or open sores of the jaw bone that won't heal and are hard to treat. Some people develop ONJ after dental work (such as having a tooth pulled) is done while on this medicine. Many cancer doctors advise patients 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 might also help prevent this condition.
Denosumab (Xgeva™) is another drug that can help when cancer spreads to bone. Like the bisphosphonates, this drug keeps osteoclasts from being turned on, but it does so in a different way, by blocking a substance called RANKL.
Studies have shown that it can help prevent or delay problems like fractures in patients with bone metastases at least as well as zoledronate. It also can be helpful when zoledronate is no longer working.
This drug is injected under the skin every 4 weeks. Patients given this drug may need 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 cause ONJ, so doctors recommend taking the same precautions (such as having tooth and jaw problems treated before starting the drug). Unlike the bisphosphonates, this drug is safe to give to patients with kidney problems.
Last Medical Review: 05/03/2012
Last Revised: 05/03/2012