Bone Cancer

One of the less common cancers is that of the bone. Bone cancer occurs throughout the world and thus makes an impact on global health resources. Cancer of the bone rarely begins in the bone itself; more often, it is a result of cancer spreading from elsewhere in the body. Cancer that originates within bone cells is a primary bone cancer; if the cancer is a spreading of another tissue's cancer, it is secondary bone cancer. Additionally, most tumors of the bone are benign. Only occasionally do they become cancerous.

Primary bone cancer is classified into four major categories: osteosarcoma, chondrosarcoma, Ewing's sarcoma, and spindle cell sarcoma. A sarcoma is any cancer of the connective tissues or supportive tissues. These tissues include blood vessels, bone, cartilage, fat, and muscle. Osteosarcoma, therefore, is a cancer in the bone itself. This type of cancer starts while the bone is still growing; thus, affected people are typically between the ages of 10 and 25 years old. An osteosarcoma will usually occur at the ends of long bones. Two common locations for such a sarcoma are in the thigh bone (femur) or shin bone (tibia); thus, osteosarcomas often occur around the knees. The excess bony substance produced is called an osteoid.

Chondrosarcoma is cancer in the cartilage. Cartilage is a shiny substance that covers the ends of bones to cushion the joints. Chondrocytes are the cells that make cartilage—when chondrocytes grow and produce cartilage in an area of bone that normally would not have cartilage cover, a chondrosarcoma results. Chondrosarcomas usually begin when a person is above age 50.

The third bone cancer, Ewing's sarcoma, generally results from prior cancer treatment such as radiation or chemotherapy. It is a cancer of the nervous tissue in the bone marrow and affects younger people. These tumors are named after the surgeon who first described them, and are commonly seen in the pelvis. Along with being a bone cancer, Ewing's sarcoma is one of a group of cancers called the Ewing's family of tumors (EFT); other EFT cancers are extraosseous Ewing's (EOE), primitive neuroectodermal tumor (PNET), and Askin's tumor, or PNET of the chest wall. Although Ewing's sarcoma affects the bone, EOE is around the bone, and PNETs are not in the bone, all EFT tumors originate in the same type of stem cell.

Spindle cell sarcomas include fibrosarcoma, leiomyosarcoma, malignant fibrous histiocytoma, and undifferentiated sarcoma of bone. The undifferentiated sarcomas are from cells that have not yet differentiated into specific bone cells. The remaining kinds of spindle cell sarcomas can be diagnosed by a pathologist based upon microscopic cellular analysis.

Another type of cancer in the bones that is not in the above-mentioned categories is multiple myeloma. This cancer is of the bone marrow, typically in people between age 50 and 70. People whose lives have been affected by myeloma can often find support in groups for the cancers of the blood, which are also associated with bone marrow. These cancers include leukemia and lymphoma. There is also an International Myeloma Foundation, based in California.

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