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.
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.
This fact sheet deals with primary bone cancer.
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).
Cancers of the Bone