ON THIS PAGE: You will find some basic information about this disease and the parts of the body it may affect. This is the first page of Cancer.Net’s Guide to Bone Cancer. To see other pages, use the colored boxes on the right side of your screen. Think of those boxes as a roadmap to this full guide. Or, click “Next” at the bottom of each page.
The human skeletal system is made up of more than 200 bones that protect the internal organs, allow people to stand upright, and attach to muscles, which allow movement. Bones are connected to other bones by ligaments (bands of tough, fibrous tissue), while cartilage covers and protects the joints where bones come together. Bones are hollow and filled with bone marrow, which is the spongy, red tissue that produces blood cells. The cortex is the hard, outer portion of the bone.
See illustrations of the bone .
Bone is a tissue that consists of collagen (a soft, fibrous tissue) and calcium phosphate (a mineral that helps harden and strengthen the bone). There are three types of bone cells:
- Osteoclasts. These cells break down and remove old bone.
- Osteoblasts. These cells build new bone.
- Osteocytes. These cells carry nutrients to the bone.
About bone cancer
Cancer can occur in any part of the bone. Cancer begins when normal cells in the bone change and grow uncontrollably, forming a mass called a tumor. A bone tumor can be benign (noncancerous) or malignant (cancerous, meaning it can spread to other parts of the body). Even though a benign tumor does not spread outside the bone, it can grow large enough to press on surrounding tissue and weaken the bone. A malignant tumor can destroy the cortex and spread to nearby tissue. If bone tumor cells get into the bloodstream, they can spread to other parts of the body, especially the lungs.
There are different types of bone cancer, including:
- Osteosarcoma  and Ewing sarcoma . These are two of the most common types of bone cancer and mainly occur in children and young adults.
- Chondrosarcoma. Chondrosarcoma is cancer of the cartilage and is more common in adults.
- Chordoma. This is a type of bone cancer that typically starts in the lower spinal cord.
Rarely, soft tissue sarcomas  begin in the bone, including:
- Malignant fibrous histiocytoma (MFH). MFH makes up less than 1% of bone tumors and is usually found in adults. An arm or leg, especially around the knee joint, is the most common place for MFH to appear.
- Fibrosarcoma. This type of soft tissue sarcoma is also more common among adults, particularly during middle age. It most often begins in the thighbone.
- Paget’s disease of the bone. This disease generally occurs in older adults and involves the overgrowth of bony tissue.
This section contains information about primary bone cancer (cancer that begins in the bone). However, it is much more common for bones to be the site of metastasis (spread) from other cancers, such as breast , lung , or prostate  cancer. Cancer that started in another area of the body and has spread to the bone is called metastatic cancer, not bone cancer. For example, lung cancer that has spread to the bone is called metastatic lung cancer.
For information about cancer that has started in another part of the body and spread to the bone, please see the information for that type of cancer  or read the fact sheet about when cancer spreads to the bone .
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