Bone Metastasis

The tumors that develop from the cancer cells spreading to bones are called bone metastases.

Cancerous cells may get separated from a primary tumor mass and gain entry into the blood circulation or lymph vessels to reach almost every tissue of your body.

However, bones serve as a more common place for these cells to settle down and start propagating.

Nearly all types of cancer can spread or metastasize to the bones. The types of cancer that are more likely to spread to the bone are breast cancer and prostate cancer.

Bone metastasis may occur in any bone, but most commonly, the spine, pelvis and thigh bone.

It may often be the first sign of your cancer, or sometimes, bone metastasis will develop several years after your cancer treatment.

Bone metastasis can lead to pain and bone fractures. Except for some rare circumstances, cancer that has spread to the bones is not curable.

However, there are treatments to reduce pain and other symptoms associated with bone metastases.

Sometimes, bone metastasis does not cause any signs and symptoms and is found only when tests are performed to check for the spread of cancer.

When signs and symptoms do occur, they include:

• Bone pain: This is usually the first symptom of cancer that spreads to the bone. The pain is intermittent at first and it tends to be more severe during the night and becomes relieved by movement. As time passes, the pain become constant and worsens with movement or activity.
• Bone fracture: Bones that become weak as a result of metastatic cancer may break. The bone may get fractured during a fall or an injury, but an already weakened bone can also break while performing everyday activities. These fractures cause sudden, severe pain, making it almost impossible to move. Sometimes, a fracture is the first sign of bone metastasis. The most common bones affected by fractures are long bones in the arms and legs and vertebrae of the spine. A sudden pain arising in the mid back region is also a common symptom of a spinal bone fracture or collapse due to cancer.
• Loss of bowel and bladder control causing trouble in urinating and constipation: This symptom is due to cancer growth in the bones of the spine that press on the spinal cord and its nerves.
• Numbness and weakness in the parts of the body below the tumor, most often the arms and legs: This also happens because of spinal cord compression and damage to the spinal cord nerves
• High blood calcium levels (hypercalcemia): When cancer metastasizes to the bones, calcium in the bones gets eroded away into the bloodstream, which causes hypercalcemia and symptoms such as constipation, nausea, vomiting, loss of appetite, and an extreme feeling of thirst. The high level of calcium results in the production of more urine, which leads to dehydration. It can also cause fatigue, weakness, and confusion.

If you have persistent signs and symptoms that are concerning, consult your doctor.

Let your doctor know about your medical history, and if you have been treated for cancer in the past.

Doctors are not sure what the exact cause for bone metastasis is, and moreover, it is not known why the cancer spreads to the bone more commonly than other sites, such as the liver.

Bone metastasis occurs when cancer cells break way from the primary tumor and travel along the bloodstream or lymph vessels to enter the bones, where they start multiplying and form new tumors.

Making a diagnosis of bone metastasis is done by several procedures.

At the time you make an appointment, ask if there are any pre-appointment restrictions to be followed, such as dietary restrictions.

Make a list of the following information:

• All symptoms you have including those that seem unrelated to the reason for which you scheduled the appointment.
• Duration of your symptoms and factors that make the symptoms worse or better.
• Key personal information, including any major stresses or recent life changes.
• All medications, vitamins or supplements that you take regularly.

Ask a family member or friend to come along during your appointment.

The person who accompanies you may help remember something that you missed or forgot.
Write down questions you may want to ask your doctor.

For bone metastasis, some basic questions to ask your doctor include:

• What is most likely the cause of my symptoms?
• What kind of tests do I need?
• What treatments are available, and which one do you suggest for my condition?
• What is my prognosis?
• Are there any experimental treatments or clinical trials available to me?
• I have other health problems. How will these affect my treatment?
• Is there a generic alternative to the medicine you have prescribed?
• What will determine whether I should plan for a follow-up visit?

 Your doctor may ask you a few questions such as:

• When did you first notice your symptoms?
• Have your symptoms been continuous, or intermittent?
• What is the severity of your symptoms?
• Does anything seem to improve or worsen your symptoms?

Imaging tests are ordered to investigate the signs and symptoms that may indicate bone metastasis.

The type of test depends on your specific situation.

Tests may include:

• X-ray
• Computerized tomography (CT)
• Magnetic resonance imaging (MRI)
• Bone scan (bone scintigraphy)
• Positron emission tomography (PET)

Laboratory tests that may be ordered include:

• Tumor markers: Certain substances called tumor markers are released into the blood in some types of cancer. An abnormal increase in the tumor marker levels may indicate that the cancer has spread.
• Other blood tests include testing for calcium and alkaline phosphatase levels

Biopsies done to detect bone metastases
   

Needle biopsy-  There are two types of needle biopsies such as:

• Fine needle biopsy or aspiration: A very thin, hollow needle is inserted  to withdraw a small amount of fluid and small piece of tissue from the tumor.
• Core needle biopsy: This uses a larger needle to remove a small cylinder of tissue.

Surgical bone biopsy: Rarely needed to diagnose bone metastasis. In this procedure, the surgeon cuts the bone in order to remove a small portion of the tumor.

Treatment options for patients with bone metastasis depend on several factors that include:

• The kind of cancer you have
• The number of bones the cancer has spread to
• Whether the bones have become weak or broken
• The type of treatments that you have already had
• Your symptoms
• Your general health condition

The treatment for bone metastasis includes medication, radiation therapy and surgical therapy.

Medication

The medications prescribed in patients with bone metastasis include:

• Bone-building medications: Medications that are commonly prescribed in patients with thinning bones (osteoporosis) may also be used in people with bone metastasis. These medications strengthen the bones and decrease the pain caused by bone metastasis, thus eliminating the need to take strong pain medications. Bone-building medications may also decrease your risk of developing new bone metastasis. These medications are administered intravenously every few weeks through a vein in your arm or through an injection. Oral forms of these drugs are available, but are not as effective as the IV forms and are liable to cause digestive tract side effects. Bone-building medications may cause temporary bone pain, kidney problems, and increase your risk of a serious deterioration of your jawbone (osteonecrosis).
• Chemotherapy: If multiple bones are affected by cancer cells, your doctor may recommend chemotherapy. Chemotherapy drugs travel throughout your body to fight against cancer cells. Chemotherapy drugs are available in the form of pills, administered through a vein or both. Side effects are specific to the chemotherapy drug given. Chemotherapy is the best way to alleviate pain from bone metastases in cancers that are sensitive to chemotherapy.
• Hormone therapy: Hormone therapy involves taking medications to lower natural hormone levels or medications that hinder the interaction taking place between hormones and cancer cells. With treatment of cancers that are sensitive to hormones released in the body, suppression of those hormones may be an option. Breast cancer and prostate cancer responds well to hormone-blocking treatments. Another option is surgery for the removal of hormone-producing organs — the ovaries, in women, and the testes, in men.
• Pain medications: Pain medications can reduce the pain caused by bone metastasis. Pain medications include over-the-counter pain relievers, such as ibuprofen (Advil, Motrin IB, others), or stronger prescription pain relievers, such as morphine (Avinza, MS Contin, others). It may take some time to derive a perfect combination of pain medications that is effective for you. If you are on pain medications but still having pain, inform your doctor. A pain specialist will be able to advise you on additional pain-relieving options.
• Steroids: Steroids can decrease the swelling and inflammation around the sites of cancer, and thereby relieve pain associated with bone metastasis. These medications work rapidly to reduce pain and prevent some cancer complications, but these should be used with caution as these lead to side effects, if taken for prolonged periods.
• Targeted therapy: There are a new class of medications available to treat many cancers. These medications attack specific abnormalities of the cancer cells. Some types of cancers react very well to targeted therapy. For example, breast cancer cells that are HER2 positive will respond to trastuzumab (Herceptin) therapy.
• External radiation therapy: Radiation therapy involves the use of high-powered energy beams such as X-rays to kill the cancer cells. This treatment may be an option if your bone metastasis is causing pain that cannot be controlled by pain medications or if the pain is confined to a small area. Depending on your condition, radiation to the bone is administered in one single large dose or in several smaller doses over a period of time. The side effects of radiation depend on the site being treated and its size.

Surgery

Surgical procedures are performed to repair a broken bone or to stabilize a bone that is at a risk of breaking.

• Surgery to stabilize the bone: If the bone is at a greater risk of undergoing a fracture due to bone metastasis, surgeons stabilize the bone with the use of metal plates, screws and nails (orthopedic fixation). Orthopedic fixation relieves pain and improves function. Often, radiation therapy is given once healing is complete after surgery.
• Surgery to inject a bone with cement: Bones that are not able to be stabilized with metal plates or screws, such as pelvic bones and bones in the spine, may benefit from an injection of quick-setting bone cement or glue called polymethyl methacrylate (PMMA). Doctors inject bone cement into a bone that has been damaged or broken due to bone metastasis. This procedure helps reduce pain.
• Surgery to repair a broken bone: If bone metastasis has caused a bone fracture, surgeons may repair the bone. This involves the use of metal plates, screws and nails to stabilize the bone. Joint replacement, such as a hip replacement is another option. Usually, broken bones caused by bone metastasis cannot benefit from the placement of a cast on the broken bone.

Alternative treatments

• Heating and freezing cancer cells: The procedures that kill cancer cells with heat or cold can help control pain. These procedures are an option if you have one or two areas of bone metastasis that have not responded to other treatments. During a procedure called radiofrequency ablation, a needle with an electric probe is passed into the bone tumor. Electricity enters through this probe and produces heat in the surrounding tissues. Then the tissue is allowed to cool down, after which the process is repeated. A similar procedure called cryoablation is performed in which the tumor is frozen and then allowed to thaw. This process is repeated several times. Side effects that may occur include damage to surrounding structures, such as nerves and this can increase the risk of a broken bone.
• Intravenous radiation: A form of radiation called radiopharmaceuticals, which can be given intravenously is useful for patients with multiple bone metastases. Radiopharmaceuticals consist of low levels of radioactive material that have a strong attraction to bones. Once these enter your body, the materials travel to the areas of bone metastasis and release their radiation. Radiopharmaceuticals can control pain caused by bone metastasis. Side effects such as damage to bone marrow can lead to low blood cell counts.
• Clinical trials: Clinical trials involve studies of new treatments or new ways of using existing treatment methods. Enrolling yourself in a clinical trial gives a chance to try the latest treatments, although a cure is not guaranteed, and there may be unknown side effects of new treatments. Discuss the available clinical trials with your doctor.
• Physical therapy: A physical therapist can suggest an exercise plan that will help you increase your strength and improve your mobility. Assisting devices may be recommended to help you cope with your situation. Examples include use of crutches or a walker to take weight off from affected bone while walking, a cane to improve your balance, or a brace to stabilize the spine.

Coping with bone metastasis requires a little more than just bearing the bone pain.

It involves coming to terms with the fact that your cancer has spread beyond its primary site.

Cancer that has spread to a secondary site may be very difficult to cure, but people with bone metastasis can live for several years.

Your doctor will advise you on ways to minimize your pain and maintain function so that you can continue performing your daily activities.

Each person can find their own individual way to cope with a cancer diagnosis.

Until you find the route that is best for you, consider trying to:

• Find out enough information about bone metastasis so that it will be easier to make decisions about your care.
• Discuss with your doctor the details of your cancer and treatment options available.
• Ask about some trustworthy sources to collect further information. If you can research on your own, good websites to start with include the National Cancer Institute and the American Cancer Society.
• Find someone to share your feelings with: Even though your friends and family members are always your best allies, in some cases it may become hard for them to cope with the shock of your diagnosis. In these cases, you might want to talk to a counselor, a medical social worker, or a pastoral or religious counselor. Ask your doctor for a referral.
• Try connecting with other cancer survivors: You may find some comfort by discussing your problems with other cancer survivors as they can provide unique insight into your situation. Contact your local chapter of the American Cancer Society to find cancer support groups in your area.
• Come to terms with your diagnosis: Coming to terms with the fact that your cancer is no longer curable may be hard. For some people, having a strong faith or a sense of something greater than themselves makes this process easy. Others may feel comfortable after seeking counseling from someone who understands life-threatening illnesses better, such as a medical social worker, psychologist or chaplain. Some people also take measures to ensure that their last wishes are known and respected by writing them down and discussing them with their loved ones.

Having a cancer that is identified after it has spread to other organs increases your risk of getting bone metastasis.

Cancers affecting certain organs such as the breast, prostate, lung, thyroid, and kidney are more likely to spread to bones than others.

Among the same types of cancer, the tumors that are large and have spread to the lymph nodes are more likely to metastasize to the bone.

In some cancers, a high grade cancer (abnormal cancer cells under a microscope) with certain genetic changes make it more likely to spread to bones.