Bone metastasis

Bone metastasis

Definition:
Bone metastasis occurs when cancer cells spread from their original site to a bone. Nearly all types of cancer can spread (metastasize) to the bones. But some types of cancer are particularly likely to spread to bone, including breast cancer and prostate cancer.

Bone metastasis can occur in any bone but more commonly occurs in the pelvis and spine. Bone metastasis may be the first sign that you have cancer, or bone metastasis may occur years after cancer treatment.

Bone metastasis can cause pain and broken bones. With rare exceptions, cancer that has spread to the bones can't be cured. Treatments can help reduce pain and other symptoms of bone metastases.


Symptoms:
Signs and symptoms of bone metastasis include:

• Bone pain
• Broken bones
• Urinary incontinence
• Bowel incontinence
• Weakness in the legs
• High levels of calcium in the blood (hypercalcemia), which can cause nausea, vomiting and confusion

When to see a doctor
If you experience persistent signs and symptoms that worry you, make an appointment with your doctor. If you've been treated for cancer in the past, tell your doctor about your medical history and that you're concerned about your signs and symptoms.


Causes:
Bone metastasis occurs when cancer cells break away from the original tumor and spread to the bones, where they begin to multiply. It's believed that cancer cells arrive in the bones by traveling through the blood vessels.

Doctors aren't sure what causes some cancers to spread. And it's not clear why some cancers travel to the bones rather than to other common sites for metastasis, such as the liver.

Treatments and drugs:

Treatments for bone metastasis include medications, radiation therapy and surgery. What treatments are best for you will depend on the specifics of your situation.
Medications
Medications used in people with bone metastasis include:

• Bone-building medications. Drugs commonly used to treat people with thinning bones (osteoporosis) may also help people with bone metastasis. These medications can strengthen bones and reduce the pain caused by bone metastasis, reducing the need for strong pain medications. Bone-building medications may also reduce your risk of developing new bone metastasis. These drugs can be administered every few weeks through a vein in your arm or through an injection. Bone-building medications can cause temporary bone pain and kidney problems. They increase your risk of a rare but serious deterioration of your jawbone (avascular osteonecrosis).
  
• Chemotherapy. If cancer has spread to multiple bones, your doctor may recommend chemotherapy. Chemotherapy travels throughout your body to fight cancer cells. Chemotherapy can be taken as a pill, administered through a vein or both. Side effects depend on the specific chemotherapy drugs you are given.
  
• Hormone therapy. For cancers that are sensitive to hormones in the body, treatment to suppress those hormones may be an option. Breast cancers and prostate cancers are often sensitive to hormone-blocking treatments. Hormone therapy can involve taking medications to lower natural hormone levels or medications that block the interaction between hormones and cancer cells. Another option is surgery to remove hormone-producing organs — in women, the ovaries, and in men, the testes.
  
• Pain medications. Pain medications may control the pain caused by bone metastasis. Pain medications may include over-the-counter pain relievers, such as ibuprofen (Advil, Motrin, others), or strong prescription pain relievers, such as morphine (Avinza, MS Contin, others). It may take time to determine what combination of pain medications works best for you. If you're taking medications but still experiencing pain, tell your doctor.

External radiation therapy
Radiation therapy uses high-powered energy beams, such as X-rays, to kill cancer cells. Radiation therapy may be an option if your bone metastasis is causing pain that isn't controlled with pain medications. Depending on your situation, radiation to the bone can be administered in one large dose or several smaller doses over many days. Side effects of radiation depend on the site being treated. In general, radiation therapy causes skin redness and fatigue.
Surgery
Surgical procedures can help stabilize a bone that is at risk of breaking or repair a broken bone.

• Surgery to stabilize the bone. If the bone is in danger of breaking due to bone metastasis, surgeons can stabilize the bone using metal plates, screws and nails (orthopedic fixation). Orthopedic fixation can relieve pain and improve function. Often, radiation therapy is given after you have healed from surgery.
  
• Surgery to inject a bone with cement. Bones that can't be easily reinforced with metal plates or screws, such as pelvic bones and bones in the spine, may benefit from bone cement. Doctors inject bone cement into a bone that is broken or damaged by bone metastasis. This procedure can reduce pain.
  
• Surgery to repair a broken bone. If bone metastasis has caused a bone to break, surgeons may work to repair the bone. This involves using metal plates, screws and nails to stabilize the bone. Joint replacement, such as a hip replacement, may be another option. In general, broken bones caused by bone metastasis aren't helped by placing a cast on the broken bone.

Heating and freezing cancer cells
Procedures to damage cancer cells with heat or cold may help control pain. These procedures may be an option if you have one or two areas of bone metastasis and aren't helped by other treatments.
During a procedure called radiofrequency ablation, a needle containing an electric probe is inserted into the bone tumor. Electricity passes through the probe and heats the surrounding tissue. The tissue is allowed to cool down, and the process is repeated. A similar procedure called cryoablation freezes the tumor and then allows it to thaw. The process is repeated multiple times.
Side effects can include damage to nearby structures, such as nerves, and damage to bones that can increase the risk of a broken bone.

Intravenous radiation
For people with multiple bone metastases, a form of radiation called radiopharmaceuticals can be given through a vein. Radiopharmaceuticals use low levels of radioactive material that has a strong attraction to bones. Once in your body, the particles travel to the areas of bone metastasis and release their radiation.

Radiopharmaceuticals can help control pain caused by bone metastasis. This treatment doesn't require a hospital stay, and you won't be radioactive after treatment. Side effects can include damage to the bone marrow, which can lead to low blood cell counts.

Clinical trials
Clinical trials are studies of new treatments and new ways of using existing treatments. Enrolling in a clinical trial gives you the chance to try the latest treatments. But a cure isn't guaranteed, and the side effects of new treatments may not be known. Discuss the available clinical trials with your doctor.

Physical therapy
A physical therapist can work with you to devise a plan that will help you increase your strength and improve your mobility. A physical therapist may suggest assistive devices to help you cope. Examples might include crutches or a walker to take weight off an affected bone while walking, a cane to improve balance, or a brace to stabilize the spine. A physical therapist may also suggest specific exercises to help you keep your strength up and reduce your pain.