Bone cancer is a type of cancer in which normal bone (or bone-associated) cells undergo a change and become cancerous. Bone cancer is quite rare; however, cancer that starts in the bone does occur. There are three main types of bone cancer: osteosarcoma, chondrosarcoma and Ewing's sarcoma. These cancers differ by the type of cell that becomes malignant.
Osteosarcoma
According to the Mayo Clinic, osteosarcoma begins directly in the cells of the bone. The National Cancer Institute refers to this tissue as osteoid tissue. According to the Mayo Clinic, this type of cancer most often affects children and young adults. The bones of children and young adults are rapidly growing, which means the cells of the bone are dividing at a rapid rate. Every time a cell divides, there is a chance (though a minuscule one) that it may change in such a way that it becomes cancerous and grows uncontrollably. Because children and young adults have rapidly dividing osteoid cells as they grow from children to adults, there are more chances for the cell to become cancerous.
Chondrosarcoma
Chondrosarcoma is a cancer in which the originating cell that becomes cancerous is the cartilage attached to the bone. According to the National Cancer Institute, cartilage pads the ends of bones, cushioning the bones where they may interact in the joints. Chondrosarcoma most often occurs in the upper legs, shoulder and pelvis region. This type of cancer usually affects adults over the age of 50.
Ewing's Sarcoma
According to the National Cancer Institute, Ewing's sarcoma can arise in the bone or in other soft tissue connected to bone, such as blood vessels, fibrous tissue, muscles or fat. The Mayo Clinic reports that Ewing's sarcoma is more of an enigma to scientists than the other two types of bone cancer. It is not clear exactly where in the bone this type of cancer begins, but scientists believe it begins in the nerves embedded within the bone. This type of cancer often affects young adults who have a different condition that is being treated with chemotherapy or radiation. Ewing's sarcoma most often affects the backbone and pelvis, according to the National Cancer Institute.
Metastases
The National Cancer Institute reports that bone cancer can also result from the spread of other cancers, such as from the breast, lung or prostate. When a cancer spreads in this manner it is called metastatic cancer, and is named for the organ in which the cancer originated. For example, a person who has breast cancer that spreads to the bone has metastatic breast cancer.
