Bone Cancer

Bone cancer is a malignant growth that can be found in any part of the bone, in any bone of the body.  The cancer may originate in the bone itself (primary bone cancer) or – more commonly – it may be a result of a cancer that has spread (metastasized) from elsewhere in the body (secondary bone cancer).

Bone cancer is a growth found in any part of the bone.  Most bone cancers are called sarcomas, cancers that develop predominantly from bone, cartilage, muscle, fibrous tissue, fatty tissue, or nerve tissue.  Bone cancer originating in the bone itself is known as primary bone cancer, and may be malignant (cancerous) or benign.

Types of Bone Cancer

Primary Bone Cancers:

• Osteosarcoma – The most common type of primary bone cancer, osteosarcoma, develops in new tissue of growing bones, particularly the knees, upper legs, upper arms, often spreading to other parts of the body before it causes any symptoms.  This cancer affects children and young people between the ages of 10 and 25.  Symptoms include pain, swelling, and tenderness most commonly above or below the knee.
• Ewing's Sarcoma – Ewing's sarcoma begins in immature nerve tissue in the bone marrow of the body's large bones: the pelvis, upper legs, ribs and arms, and can spread to other parts of the body at an early stage.  Like osteosarcoma, Ewing's sarcoma most frequently affects children and young adults.  Here, too, symptoms include pain, swelling, and tenderness; the weakened bone is also more prone to fracture.
• Chondrosarcoma – Chondrosarcoma arises in the cartilage (soft connective tissue) of the pelvis, upper legs and shoulders.  This type of malignancy most frequently affects adults over the age of 50, and may develop from a prior benign tumor.  Symptoms include pain, swelling, and tenderness.  Unlike the above cancers, chondrosarcoma tumors grow slowly and do not immediately spread to other parts of the body.

Secondary Bone Cancer:

• Secondary or metastatic bone cancer spreads from a primary site to elsewhere in the body.  It is more common than primary bone cancer and usually occurs later in life.  Cancers that tend to spread rapidly to bone include those of the breast, lung, prostate, thyroid, and kidney.  Symptoms include bone pain, primarily occurring at night, and bones that easily fracture.

Contributing Risk Factors

Primary bone cancers occur more frequently in children and young adults, particularly in those who have had radiation or chemotherapy treatments for other conditions.

Signs and Symptoms

As bone tumors grow, they compress, absorb or replace healthy bone tissue with abnormal tissue, causing a number of symptoms, including bone pain, swelling, and bone weakness.

Pain is the most common symptom of bone cancer, often the result of weakening bones or a tumor that invades bone or presses against nerves or other tissues.  Swelling and tenderness in or near joints is also common.  Frequent fractures may be an indication of cancer, as bones weakened by tumors are more susceptible to injury.  Symptoms may also include fatigue, fever, weight loss, and anemia (loss of oxygen-carrying red blood cells).  All of these symptoms can mimic those of other less serious conditions, so it is important to confirm them with your doctor.

Treatment and Prevention

Conventional approaches to control bone pain include analgesics (to relieve pain) with treatments that kill cancer cells (chemotherapy or radiation therapy), slow their growth (hormonal therapy), or reduce bone damage (bisphosphonates).

Bisphosphonates are a newer type of drug that has proved to be very successful in relieving the bone pain caused by bone cancer.  Cancer cells stimulate bone destruction which in turn releases cytokines or growth factors that stimulate cancer cell growth.  Also, in many types of bone cancer, abnormally high levels of osteoclasts lead old bone to break down faster than new bone can be formed.  This malfunction leads to a number of problems, including bone pain and the weakening of bones.  Bisphosphonates work by inhibiting the activity of the bone-destroying osteoclast cells.  Some researchers have even shown that bisphosphonates can shrink or prevent metastatic tumors, although more research is needed in this area.  Bisphosphonates may be taken orally or given intravenously.  Intravenous use is most common, as these drugs are difficult for the digestive system to absorb and they may cause irritation and ulcers in the esophagus when taken orally.  IV bisphosphonates are also more potent than the oral bisphosphonates and generally have a quick infusion time (sometimes in as little as 15 minutes).  Researchers have found that the more potent the dose and the earlier the patient begins bisphosphonate therapy, the better the outcome.

Patients generally receive a combination of therapies judged most likely to be effective by a doctor.  Many therapies have a palliative function (meant to relieve pain and other symptoms) rather than a curative (meant to cure cancer) function, though doctors may attempt to cure primary bone cancer in some patients.  Thanks to the many successful treatment methods for bone pain caused by cancer, most patients will feel little to no pain from bone cancer.

Depending on the therapy used, side-effects vary.  Many different drugs or drug combinations can be used to treat bone pain caused by bone cancer.  These drugs may be used in combination with surgery, radiation, and other treatments which can affect the way the body handles medication, as well as cause their own side-effects.

Prognosis

Treatments for bone cancer are increasingly successful; even for the more aggressive cancers, survival rates are improving considerably.