Bone is the framework that supports the body. Most bones are hollow. Bone marrow is the soft tissue inside hollow bones. The bone itself is very hard and strong. At each end of the bone is a softer bone-like tissue called cartilage that acts as a cushion between bones. The outside of the bone is covered with a layer of fibrous tissue.

The bone itself is made up of 2 kinds of cells. Osteoblasts are cells that form the bone. Osteoclasts are cells that dissolve bone. Although we think that bone does not change, the truth is that it is very active. New bone is always forming and old bone dissolving.

The marrow of some bones is made up only of fatty tissue. In other bones the marrow is a mixture of fat cells and blood-forming cells. These blood-forming cells make red blood cells, white blood cells, and platelets.

All of these parts of bone can develop into cancer.

Types of Bone Cancers

Most of the time when someone is told they have bone cancer, the doctor is talking about a cancer that started somewhere else and then spread to the bone. This is called metastatic cancer and can happen to people with advanced breast cancer, prostate cancer, and lung cancer, as well as many others. When these cancer cells are looked at under a microscope, they look like the cancer cells that they came from. If someone has lung cancer that has spread to the bone, the cells there will look and act like lung cancer cells and they will be treated the same way.

To learn more about cancer that has spread to the bones, please see “Bone Metastases” as well as the document on the place where the cancer started (“Breast Cancer,” “Prostate Cancer,” etc.)

Other kinds of cancers that are sometimes called “bone cancers” start in the bone marrow—in the blood-forming cells. The most common of these is multiple myeloma. Certain lymphomas (which more often start in lymph nodes) and all leukemias start in bone marrow. You can get more information about all of these types of cancers from the American Cancer Society.

The main type of true bone cancers are called sarcomas. A sarcoma is a cancer that starts in connective tissue such as bone, muscle, tendons, ligaments, or some other tissues in the body.

Primary Bone Tumors

There are several different types of bone tumors. Their names are based on the bone or tissue that is involved and the kind of cells that make up the tumor. Some are cancerous (malignant). Others are not cancerous (benign). Most bone cancers are called sarcomas.

Benign bone tumors do not spread to other tissues and organs. They can usually be cured by surgery. This information does not cover benign bone tumors.

Cancerous Bone Tumors

Osteosarcoma: Osteosarcoma is cancer of the bone itself. It most often occurs in young people between the ages of 10 and 30. But about 10% of cases occur in people in their 60s and 70s. This cancer is rare during middle age. More males than females get this cancer. These tumors start most often in bones of the arms, legs, or pelvis. For more information see the ACS document "Osteosarcoma."

Chondrosarcoma: This is a cancer of cartilage cells and is the second most common true bone cancer. Chondrosarcoma is not often found in people younger than 20. After age 20, the risk of this cancer keeps on rising until about age 75. It occurs in men and women at about the same rate.

Cartilage is softer than bone but more firm than most other tissues. Ears are mainly cartilage. Cartilage is actually the tissue from which most bones form. It is mainly found at the end of long bones and at the place in the chest where the ribs meet the breastbone. Chondrosarcoma most often starts in cartilage of the pelvis, leg or arm, but it can start in many other places as well.

Chondrosarcomas are given a grade, depending on how fast-growing they are. A lower grade means the cancer is not likely to spread while a high grade means it is more likely to spread. Most are low grade. There are also other differences among chondrosarcomas that can be seen under a microscope which help to predict the response to treatment and outlook for survival.

Ewing tumor: This cancer is named after Dr. James Ewing, the doctor who first described it in 1921. Unlike osteosarcoma, Ewing tumors form in the hollow part of the bone. This cancer usually appears in children and teenagers. It is not common in adults over 30 years old. For more information see the ACS document “Ewing Family of Tumors."

Fibrosarcoma and malignant fibrous histiocytoma: These cancers usually start in the soft tissues around bones (such as ligaments, tendons, fat, and muscle) rather than the bone itself. They usually occur in older and middle-aged adults. These cancers most often affect bones of the legs, arms, or jaw.

Giant cell tumor of bone: This type of bone tumor has both benign and malignant forms. Only about 10% of giant cell bone tumors are cancerous and spread to other parts of the body. But they often come back after surgery. When they do come back after surgery they are more likely to spread to other parts of the body. These tumors often affect the arm or leg bones of young and middle-aged adults.

Chordoma: This tumor usually occurs in the base of the skull and bones of the spine. It is found most often in adults older than 30 years, and is about twice as common in men than in women. Chordomas tend to grow slowly and usually do not spread to other parts of the body, but they often come back in the same place if they are not removed completely. When they do spread, lymph nodes, the lungs, and the liver are the most common places.

Other types: Two other types of cancer can start in bone but they are covered in separate documents. Please see "Non-Hodgkin Lymphoma" and "Multiple Myeloma" for more information about these cancers. Last Revised: 06/14/2006