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About bone

Bone is the framework that supports the body. Most bones are hollow. Bone marrow is the soft tissue inside hollow bones. The main substance of bone is made up of a network of fibrous tissue onto which calcium salts are laid down. This makes the bone 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 contains 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 only fatty tissue. In other bones the marrow is a mixture of fat cells and the cells that make blood cells. These blood-forming cells make red blood cells, white blood cells, and platelets.

Types of bone tumors

Most of the time when someone is told they have cancer in their bones, the doctor is talking about a cancer that started somewhere else and then spread to the bone. This is called metastatic cancer (not bone cancer). This can happen to people with many different types of advanced cancer, such as breast cancer, prostate cancer, lung cancer, and many others. Under a microscope, theses cancer cells in the bone 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 bone, please see the American Cancer Society document Bone Metastasis, as well as the document on the place where the cancer started (Breast Cancer, Lung Cancer (Non-Small Cell), Prostate Cancer, etc.).

Other kinds of cancers that are sometimes called “bone cancers” start in the bone marrow – in the blood-forming cells – not the bone itself. These are not true bone cancers. The most common of these is multiple myeloma. Certain lymphomas (which more often start in lymph nodes) and all leukemias start in bone marrow. To learn more about these cancers, refer to the document for each.

A primary bone tumor starts in the bone itself. True (or primary) bone cancers are called sarcomas. A sarcoma is a cancer that starts in bone, muscle, tendons, ligaments, fat tissue, or some other tissues in the body.

Bone tumors

There are 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 cancer (malignant). Others are not cancer (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. The information here does not cover benign bone tumors.

Bone tumors that are cancer (malignant)

Osteosarcoma: Osteosarcoma (also called osteogenic sarcoma) is the most common true bone cancer. It is most common in young people between the ages of 10 and 30. But about 10% of cases are 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. This type of bone cancer is not discussed in this document, but is covered in detail in our document, Osteosarcoma.

Chondrosarcoma: This is cancer of the cartilage cells. Cartilage is a softer form of bone-like tissue. Chondrosarcoma is the second most common true bone cancer. It is rare in people younger than 20. After age 20, the risk of this cancer keeps on rising until about age 75. Women get this cancer as often as men.

Chondrosarcomas can develop in any place where there is cartilage. It most often starts in cartilage of the pelvis, leg, or arm, but it can start in many other places, too.

Chondrosarcomas are given a grade, which measures how fast they grow. The lower the grade, the slower the cancer grows. When cancer grows slowly, the chance that it will spread is lower and the outlook is better. There are also some special types of chondrosarcoma that respond differently to treatment and have a different outlook for the patient. These special types look different when seen under a microscope.

Ewing tumor: This cancer is also called Ewing sarcoma. It is named after Dr. James Ewing, the doctor who first described it in 1921. It is the third most common bone cancer. Most Ewing tumors start in bones, but they can start in other tissues and organs. This cancer is most common in children and teenagers. It is rare in adults older than 30. This type of bone cancer is not discussed in this document, but is covered in detail in our document, Ewing Family of Tumors.

Malignant fibrous histiocytoma (MFH): This cancer more often starts in the soft tissues around bones (such as ligaments, tendons, fat, and muscle) rather than in the bone itself. If it starts in the bones, it most often affects the legs or arms. It usually occurs in older and middle-aged adults. MFH mostly tends to grow into nearby tissues, but it can spread to distant sites, like the lungs. (Another name for this cancer is pleomorphic undifferentiated sarcoma.)

Fibrosarcoma: This is another type of cancer that starts more often in “soft tissues” than it does in the bones. Fibrosarcoma usually occurs in older and middle-aged adults. Leg, arm, and jaw bones are most often affected.

Giant cell tumor of bone: This type of bone tumor has both benign (not cancer) and malignant forms. The benign form is most common. These don’t often spread to distant sites, but after surgery they tend to come back where they started. Each time they 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. It 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, they tend to go to the lymph nodes, lungs, and liver.

Last Medical Review: 12/05/2012
Last Revised: 01/24/2013