Primary Bone Cancer: Introduction

What is cancer?

Your body is made up of tiny building blocks called cells. Normal cells grow when your body needs them, and die when your body does not need them any longer. Cancer happens when cells in the body change and grow out of control. 

Cancer is made up of abnormal cells that grow even though your body doesn't need them. In most cancers, the abnormal cells grow to form a lump or mass called a tumor. If cancer cells are in the body long enough, they can grow into (invade) nearby areas. They can even spread to other parts of the body (metastasize).

What is primary bone cancer?

Primary bone cancer is cancer that starts in your bones. It is also sometimes just called bone cancer.

Primary bone cancer is different from secondary, or metastatic, bone cancer. Secondary bone cancer starts in another part of the body and spreads to the bones. If the cancer starts somewhere else, it is not called bone cancer. Instead, it keeps the name of the organ where it started. Lung cancer that spreads to the bone is still called lung cancer, for example. Or it may be called metastatic lung cancer. The cancer cells in the bone look and are treated like the cancer cells in the lung. Many types of cancer tend to spread to bone. 

Leukemia is a different type of cancer that begins in the soft, inner parts of certain bones. This soft inner part is called the bone marrow. It is considered a blood cancer, not a bone cancer.

Primary bone cancers are quite rare in adults. Most of the time, when an adult has cancer in the bones, it has spread there from another part of the body.

Primary bone tumors can be noncancerous (benign) or cancerous (malignant). Benign tumors don’t spread and are not usually life-threatening. They are generally removed with surgery. Cancerous tumors can spread and can be life-threatening.

Understanding the bones

The bones have a number of different functions in the body:

• Some bones help protect our vital organs.

• They give the body structure and form.

• Some bones, such as those in the arms and legs, make a framework for our muscles that helps us move.

• Bones also act as a place in the body to store minerals such as calcium.

The 2 main types of cells in our bones help them stay strong and keep their shape:

• Osteoblasts are cells that build new bone by forming the bone matrix. This is the connective tissue and minerals, such as calcium, that give bone its strength.

• Osteoclasts are cells that break down and remove old bone matrix. This helps bones keep their proper shape.

Bone is a living tissue that's always changing. Old cells are broken down and new ones are made to keep bones strong and healthy. By putting in or taking out minerals from the bones, osteoblasts and osteoclasts also help control the levels of these minerals in the blood.

Like other tissues of the body, bones have many other kinds of living cells as well. Any of these cells can develop into cancer.

What types of cancer can start in the bones?

Primary bone cancers are called sarcomas. Sarcomas can grow from bone, cartilage, fatty tissue, fibrous tissue, muscle, or nerve tissue.

The main types of bone cancer:

• Osteosarcoma. This is the most common primary bone cancer. It usually starts in bones of the arms or legs near where new bone is made. Most people who get this cancer are between 10 and 30 years of age. But it can occur at any age. It tends to be more common in males than in females. Most tumors occur near the knee, pelvis, or shoulder, but they can happen in any bone.

• Chondrosarcoma. This is the second most common primary bone cancer. This cancer most often is seen in older adults. It is equally common in men and women. The cancer develops in cartilage cells and is most common around the arm, leg, and hip bones. But it can occur in any bone.

• Ewing sarcoma. This cancer affects mainly children and teenagers. It is also referred to as Ewing tumor. Most of these tumors start in bone, but they can also occur in the soft tissues of the limbs, such as in muscles. Ewing sarcoma usually is found in the thigh bone, pelvis, or chest wall. But can occur in any bone.

• Fibrosarcoma and malignant fibrous histiocytoma. These cancers are most commonly found in soft tissues such as ligaments, tendons, fat, and muscle around bone. But they can develop in bones. They usually affect the legs, arms, or jaw. Older adults are most likely to get these types of cancers.

• Giant cell tumors of bone. These tumors are almost always benign. But in rare cases they can be cancer. They are most often found around the knee or shoulder and sometimes other bones in young to middle-aged adults. They don't often spread to other sites, but tend to return after they are surgically removed. With each return, the chances of the cancer spreading to other parts of the body increases. There is also a soft tissue tumor called giant cell tumor. But this is not related to this bone tumor.

• Chordoma. This type of tumor usually grows at the base of the skull or in the spine. Less often, it occurs in other parts of the spine. These tumors tend to grow slowly and seldom spread. But they often come back after surgery is done to remove them. Chordoma is most common in adults who are 30 years of age and older. It is about twice as common in men than in women.

Talk with your healthcare provider

If you have questions about bone cancer, talk with your healthcare provider. Your healthcare provider can help you understand more about this cancer.