What is Bone Cancer?
Quite often, bone cancer is the result of metastasis. This means that a cancer from elsewhere has spread to the bone. These cancers show the original cancerous cells and not those associated with bone cancer. In these cases, the cancer is treated by following the original course of treatment for the initial tumor.
But there are also primary cancers of the bone. This means that the cancer starts in the bone. Primary bone cancer is not common. Only 2 of every 1000 cancers diagnosed in the US each year are primary bone cancer. Bones are composed of:
- Osteoid tissue (hard or compact)
- Cartilaginous tissue (tough, flexible)
- Fibrous tissue (threadlike), and
- Bone marrow (soft, spongy tissue in the center of most bones)
The type of bone cancer depends on where in the bone it starts.
Common Types of Bone Cancer
- Ewing Sarcoma
- Malignant Fibrous Histiocytoma
- Giant Cell Tumor of Bone
This is one of the primary and most common bone tumors. It arises from osteoid tissue in the bone and is often found in the knee and upper arm. It is most often found in young people (aged 10-30) but also can be found in older people (aged 60-70.)
This type begins in cartilaginous tissue, which is found at the ends of bones. These tumors are most often found in the pelvis, upper leg, and shoulder. Less often, they will develop in the trachea, larynx, or chest wall. Sometimes a chondrosarcoma contains cancerous bone cells. In that case, doctors classify the tumor as an osteosarcoma.
Chondrosarcomas have different features, which can lead to a different prognosis:
- Dedifferentiated Chondrosarcomas - These begin as typical chondrosarcomas but then some parts of the tumor change into cells like those of an osteosarcoma or fibrosarcoma.
- Clear Cell Chondrosarcoma - This type grows slowly and rarely spreads to other parts of the body.
- Mesenchymal Chondrosarcomas - These can grow rapidly but can be sensitive to treatment with radiation and chemotherapy.
These normally appear in the bone but can be found in soft tissue such as muscle, blood vessels and fibrous tissues. Ewing sarcomas occur most commonly along the backbone and pelvis and in the legs and arms.
This type often starts in "soft tissue" (connective tissue) rather than in bones. However, when it develops in bones, normally it affects the legs or arms and grows quickly while also spreading to other parts of the body, like the lungs.
This cell tumor develops in both benign and malignant forms. The benign form is most common. Malignant giant cell tumor is exceedingly rare. Giant cell bone tumors typically affect the leg or arm bones of young and middle-aged adults.
This tumor normally occurs in the base of the skull and bones of the spine and grows slowly. They do not normally spread to other parts of the body. But if they are not removed completely, they will come back in the same area.
Research is increasing regarding what we know about bone cancer. Scientists are learning more about its causes. Following are common risk factors for the disease:
Genetic Disorders - A small number of bone tumors are believed to be the result of genetic mutations:
- The Li-Fraumeni Syndrome - A mutation of the p53 tumor suppressor gene makes people much more likely to develop several types of cancer, including breast cancer, brain cancer, osteosarcoma, and other types of sarcoma.
- Rothmund-Thomson Syndrome - Children with this syndrome are short, have skeletal problems, and rashes. They also are more likely to develop osteosarcoma.
- Multiple Exostoses Syndrome - Patients with this inherited condition that causes many bumps on a person's bones can have an increased risk of chondrosarcoma.
Radiation - Exposure to large doses of radiation may increase the risk of developing bone cancer. Radioactive materials such as radium and strontium can also cause bone cancer because these minerals build up in bones.
Signs and Symptoms
The most common symptom of bone cancer is pain. Persistent or unusual pain or swelling in or near a bone can be caused by cancer.
If cancer metastasizes and migrates into bones, it makes them weak. Weakened bones are more likely to break. Fractures occur most often in the leg bones near the hip because these bones support most of your weight.
Cancer in the bone may cause severe pain for a while before the bone actually breaks. It is important to consult a doctor if this occurs as an x-ray may show if the bone is likely to break.
Pain is the most common symptom of bone cancer. If a patient experiences pain, a doctor will order one of the following tests to diagnose bone cancer:
- Blood Tests
- Imaging Tests
- Bone Scan
- Computed Tomography (CAT) Scan
- Magnetic Resonance Imaging (MRI) Procedure
- Positron Emmision Tomography (PET) Scan
Removal of tissue through a needle biopsy (surgeon will make a small hole in the bone to remove a sample) or an incisional biopsy (surgeon will cut into the tumor and remove sample) to determine whether cancer is present.
This test is used to determine the level of an enzyme called alkaline phosphatase. A large amount of this enzyme is present in the blood when the cells that form bone tissue are very active.
A variety of tests is available to determine if malignant cells are present. Bone scans, CAT scans, PET scans, and MRI tests are most common.
A test in which a small amount of radioactive material is injected into a blood vessel and travels through the bloodstream. After the material pools in the bones it is then detected by a scanner.
A series of detailed images, taken from different angles, are created by a computer linked to an x-ray machine.
This uses a powerful magnet linked to a computer to create detailed scans without using x-rays.
A small amount of radioactive glucose is injected into a vein. A scanner is used to make detailed, computerized images where the glucose is used. Cancer cells often use more glucose than normal cells so the images can be used to find cancer cells in the body.
An x-ray can show the location, size, and shape of a bone tumor.
If bone cancer is diagnosed, the doctor needs to know the stage, or extent, of the disease to plan the best treatment. Staging is a careful attempt to find out whether the disease has spread, and if so, to what parts of the body. The doctor may determine the stage of bone cancer at the time of diagnosis or may need to give the patient more tests.
Treatments & Side Effects
Your treatment options will depend on the stage of bone cancer, your overall health, and your preferences about treatment. You typically have time to make your decision about your treatment. Ask questions if you do not understand any aspect of treatment or the terms your doctors are using.
It helps to learn more about the side effects from your treatment(s) before you begin, so you will know what to expect. When you know more, you can work with your health care team to manage your quality of life during and after treatment.
There are effective and readily available medications to address traditional side effects from cancer treatment (such as nausea, diarrhea, constipation and mouth sores.) Keep in mind that everyone reacts differently to treatment and experiences side effects differently. There are coping mechanisms and strategies that can help.
Treatment options for bone cancer include:
This is the primary treatment of bone cancer. It involves removal of the entire tumor so that no cancer cells are found at the edge or border of the tissue removed. Improvements in surgical techniques and treatment before surgery have made it possible for most patients with bone cancer in an arm or leg to avoid large surgical procedures (removal of the entire limb).
Surgical rehabilitation will be needed after treatment. It is much more intense after limb-salvage surgery than it is after amputation. It takes an average time of a year for patients to learn to walk again after limb-salvage involving a leg. If the patient does not take part in the rehabilitation program, the salvaged arm or leg may become useless.
Cryosurgery is the use of liquid nitrogen to freeze and kill cancer cells. This technique can sometimes be used instead of conventional surgery to destroy the tumor.
Chemotherapy involves the use of drugs to destroy cancer cells. It is a systemic (whole body) treatment. Patients who have bone cancer usually get a combination of chemo drugs. Chemotherapy is often a part of treatment for Ewing sarcoma and osteosarcoma. But it is seldom used for other bone cancers, like chondrosarcoma.
Radiation therapy is the use of high-energy rays to kill or damage cancer cells. This treatment may be used in combination with surgery. It is often used to treat chondrosarcoma, which cannot be treated with surgery. It is also used for Ewing sarcoma, where it may be combined with chemotherapy and possibly surgery.