Bone cancer is a rare disease in which cancer cells grow in the bone tissue. Cancer occurs when cells in the body, in this case bone cells, divide without control or order. Normally, cells divide in a regulated method. If cells keep dividing uncontrollably when new cells are not needed, a mass of tissue forms. This is called a growth or tumor. The term cancer refers to malignant tumors, which can invade nearby tissues and spread to other parts of the body. A benign tumor does not invade or spread.

Cancer may form in the bone or spread to the bone from another site in the body. When cancer starts in bone tissue, it is called primary bone cancer. When cancer cells travel to the bone from another site in the body, it is called secondary or metastatic cancer to the bone. Types of bone cancer include:

  • Osteosarcoma—a cancerous tumor of the bone, usually of the arms, legs, or pelvis
  • Chondrosarcoma —cancer of the cartilage
  • Ewing's sarcoma —tumors that usually develop in the cavity of the leg and arm bones
  • Fibrosarcoma and malignant fibrous histiocytoma—cancers that develop in soft tissues such as tendons, ligaments, fat, and muscle, and move to the bones of the legs, arms, and jaw
  • Giant cell tumor—a primary bone tumor that is malignant cancerous; most common in the arm or leg bones
  • Chordoma—primary bone tumor that usually occurs in the skull or spine

The cause of primary bone cancer is unknown. Genetics play a major role in most cases. Conditions that cause increased bone breakdown and regrowth over an extended period increase the risk of tumor development. This explains why osteosarcoma in children is most common during the adolescent growth spurt.