Bone Cancer Overview
Bone cancer can develop in all types of bone tissue and also in the blood-forming cells of the bone marrow (e.g., multiple myeloma, leukemia). Cancer that originates in bone is called primary bone cancer. Most cancers that originate in bone tissue are sarcomas (i.e., cancer that originates in connective tissue).
Cancer often spreads (metastasizes) to the bones from other sites in the body (e.g., breast cancer, prostate cancer, lung cancer). When this occurs, the cancer cells resemble cells from the area they originated from, not bone cancer cells. This type of cancer is called metastatic bone cancer or secondary bone cancer.
Bones are a specialized type of dense tissue (called osseous tissue) that comprises the framework of the body (the skeleton). Most bones are hollow and consist of bone cells (osteocytes) embedded in calcified tissue.
Bone tissue consists of two types of cells. Osteoblasts are responsible for bone formation and osteoclasts are responsible for dissolving bone tissue. Bone tissue is always changing: new bone cells are constantly forming and old bone cells are constantly dissolving.
Bone marrow is soft tissue inside the bones that contains blood-forming cells and other cells (e.g., fat cells, plasma cells).
Types of Bone Cancer
There are a number of different types of bone tumors. Benign bone tumors (i.e., those that do not spread) include osteomas, osteoblastomas, and osteochondromas. These types of bone tumors usually are treated surgically.
The most common type of malignant (i.e., cancerous) bone tumor is osteosarcoma, which most often develops in the bones of the arms, legs, and pelvis.
Other types of bone cancer include the following:
- Chondrosarcoma (develops in the cartilage)
- Chordoma (usually develops in the spine and the base of the skull)
- Ewing's tumor (often develops in the long bones of the arms and legs)
- Fibrosarcoma (usually develops in other types of connective tissue [e.g., ligaments, tendons])
- Giant cell tumor (may be benign; usually develops in the bone of the legs or arms)
- Malignant fibrous histiocytoma (MFH; rarely occurs in bone tissue)
Incidence & Prevalence of Bone Cancer
According to the American Cancer Society, approximately 2,970 new cases of primary bone cancer are diagnosed each year in the United States, accounting for less than .2 percent of all cancers. Osteosarcoma, which is the most common type, accounts for about 35 percent of cases; chondrosarcoma accounts for about 26 percent, and Ewing's tumor (usually affects children and adolescents) accounts for about 16 percent.
Incidence of primary bone cancer is highest in children and young adults. Osteosarcoma occurs most often between the ages of 10 and 30 and is more common in males.