Bone Cancer

Bone Cancer at a Glance

• Benign bone tumors are more common than malignant ones.
• Primary bone cancer (origin in the bones) is rare.
• There is no clearly identified cause of bone cancer, though certain factors seem to increase risk, such as high-dose radiation and hereditary retinoblastoma (an uncommon cancer of the eye).
• The common symptom of bone cancer is persistent or unusual pain or swelling in or near a bone.

What Is Bone Cancer?

Bone cancer is a malignant or cancerous tumor of the bone that destroys normal bone tissue. It is estimated that by the end of 2010, in the United States, 2,650 new cases of bone cancer would be diagnosed and 1,460 people may die from it. Bone cancer may be primary or secondary.

Primary bone cancer is cancer that forms in cells of the bone.

Secondary bone cancer is cancer that spreads to the bone from another part of the body (such as the prostate, breast, or lung).Not all bone tumors are malignant. In fact, benign (noncancerous) bone tumors are more common than malignant ones. Both malignant and benign bone tumors may grow and compress healthy bone tissue, but benign tumors do not spread, do not destroy bone tissue, and are rarely a threat to life.

Malignant tumors that begin in bone tissue are called primary bone cancer. Cancer that metastasizes (spreads) to the bones from other parts of the body, such as the breast, lung, or prostate, is called metastatic cancer, and is named for the organ or tissue in which it began. Primary bone cancer is far less common than cancer that spreads to the bones.

Incidence

Primary bone cancer is rare. It accounts for much less than 1 percent of all cancers. About 2,300 new cases of primary bone cancer are diagnosed in the United States each year. Different types of bone cancer are more likely to occur in certain populations:

• Osteosarcoma occurs most commonly between ages 10 and 19. However, people over age 40 who have other conditions, such as Paget disease (a benign condition characterized by abnormal development of new bone cells), are at increased risk of developing this cancer.
• Chondrosarcoma occurs mainly in older adults (over age 40). The risk increases with advancing age. This disease rarely occurs in children and adolescents
• ESFTs occur most often in children and adolescents under 19 years of age. Boys are affected more often than girls. These tumors are extremely rare in African American children.

Types of Primary Bone Cancer

Bones are made up of osteoid (hard or compact), cartilaginous (tough, flexible), and fibrous (threadlike) tissue, as well as elements of bone marrow (soft, spongy tissue in the center of most bones). Common types of primary bone cancer include:

• Osteosarcoma, which arises from osteoid tissue in the bone. This tumor occurs most often in the knee and upper arm.
• Chondrosarcoma, which begins in cartilaginous tissue. Cartilage pads the ends of bones and lines the joints. Chondrosarcoma occurs most often in the pelvis (located between the hip bones), upper leg, and shoulder. Sometimes a chondrosarcoma contains cancerous bone cells. In that case, doctors classify the tumor as an osteosarcoma.
• The Ewing Sarcoma Family of Tumors (ESFTs), which usually occur in bone but may also arise in soft tissue (muscle, fat, fibrous tissue, blood vessels, or other supporting tissue). Scientists think that ESFTs arise from elements of primitive nerve tissue in the bone or soft tissue. ESFTs occur most commonly along the backbone and pelvis and in the legs and arms.
  

Risk Factors

Although bone cancer does not have a clearly defined cause, researchers have identified several factors that increase the likelihood of developing these tumors. Osteosarcoma occurs more frequently in people who have had high-dose external radiation therapy or treatment with certain anticancer drugs; children seem to be particularly susceptible. A small number of bone cancers are due to heredity. For example, children who have had hereditary retinoblastoma (an uncommon cancer of the eye) are at a higher risk of developing osteosarcoma, particularly if they are treated with radiation. Additionally, people who have hereditary defects of bones and people with metal implants, which doctors sometimes use to repair fractures, are more likely to develop osteosarcoma. Ewing sarcoma is not strongly associated with any heredity cancer syndromes, congenital childhood diseases, or previous radiation exposure.