1. What are bones made of and how do they function?

Mature bones are made up of three types of tissue: compact tissue (the hard outer portion of most bones); cancellous tissue (spongy tissue inside the bones that contains bone marrow, which makes blood cells); and subchondral tissue (smooth bone tissue of the joints). A layer of cartilage covers subchondral tissue to cushion the movement of joints.

Bones support and protect internal organs, act as levers and braces for muscles to produce movement, and produce and store blood cells in the bone marrow.

2. Are all bone tumors cancerous?

Bone tumors may be benign (noncancerous) or malignant (cancerous). Benign bone tumors are more common than malignant ones. Both types may grow and compress healthy bone tissue and absorb or replace it with abnormal tissue. However, benign tumors do not spread and are rarely life-threatening.

Cancer that arises in the bone (primary bone cancer) is not the same disease as cancer that spreads to the bone from another part of the body (secondary bone cancer). Primary bone cancer is rare, with approximately 2,500 new cases diagnosed each year in the United States. More commonly, bones are the site of tumors that result from the spread (metastasis) of cancer from another organ, such as the breasts, lungs, and prostate.

3. What types of cancer arise in the bones?

The most common type of bone cancer is osteosarcoma, which develops in new tissue in growing bones. Another type of cancer, chondrosarcoma, arises in cartilage. Evidence suggests that Ewing's sarcoma, another form of bone cancer, begins in immature nerve tissue in bone marrow. Osteosarcoma and Ewing's sarcoma tend to occur more frequently in children and adolescents, while chondrosarcoma occurs more often in adults (see chart).

Types of Cancer

Tissue of Origin

Common
Locations

Common Ages

Osteosarcoma

Osteoid, upper arms

Knees, upper legs

10-25 Chondrosarcoma

Cartilage, shoulders

Pelvis, upper legs

50-60

Ewing's Sarcoma

Immature nerve tissue, usually in bone marrow

Pelvis, upper legs ribs, arms

10-20

4. What are possible risk factors for bone cancer?

Although scientists are not certain what causes bone cancer, a number of factors may put a person at increased risk. These cancers occur more frequently in children and young adults, particularly those who have had radiation or chemotherapy treatments for other conditions. Adults with Paget's disease, a noncancerous condition characterized by abnormal development of new bone cells, may be at increased risk for osteosarcoma. A small number of bone cancers are due to heredity. For example, children with hereditary retinoblastoma (an uncommon cancer of the eye) are at a higher risk of developing osteosarcoma.

5. What are the symptoms of bone cancer?

Pain is the most common symptom of bone cancer. However, symptoms may vary depending on the location and size of the cancer. Tumors that occur in or near joints may cause swelling or tenderness in the affected area. Bone cancer can also interfere with normal movements and can weaken the bones, occasionally leading to a fracture. Other symptoms may include fatigue, fever, weight loss, and anemia. None of these symptoms is a sure sign of cancer. They may also be caused by other, less serious conditions. It is important to check with a doctor.

National Cancer Institute Information Resource