Secondary bone cancer results when cancer cells—such as prostate cancer, lung cancer, or breast cancer—metastasize in the bone. After bone metastasis, the bone begins replicating prostate cancer cells or breast cancer cells, rather than the osteoblast and osteoclast cells that normally comprise healthy bones.

The exact cause of primary bone cancer is unknown, but certain factors may increase a person’s risk of developing the disease.

Several genetic disorders (hereditary syndromes) are considered risk factors for bone cancer, including:

• Li-Fraumeni syndrome, Rothmund-Thompson syndrome and mutation of the retinoblastoma gene, which puts children at increased risk of osteosarcoma
• Multiple exostoses syndrome, also called multiple osteochondromas syndrome, which increases the risk of chondrosarcoma

Some bone cancers run in families, but the underlying genetic mutations have not been identified yet. Other conditions that increase risk of bone cancer include:

• Paget’s disease of the bone (medically unrelated to the Paget’s disease of the breast), which causes bones to become thick and brittle
• Multiple enchondromatosis, which involves benign cartilage tumors known as enchondromas

These previous treatments may also play a role:

• Radiation therapy, such as the type used in cancer treatments, which may allow radioactive minerals to build up in the bones
• Bone marrow transplantation, which may increase the risk for developing osteosarcoma

Learn more about risk factors for bone cancer

Primary bone cancers are a specific subtype of a group of cancers known as sarcomas. Sarcomas are cancers that start in bone, muscle, connective tissue, blood vessels or fat, and may be found anywhere in the body. Types of bone cancers include:

• Osteosarcoma, also called osteogenic sarcoma, which is the most common type of bone sarcoma and typically starts in bone cells in the arms, legs or pelvis, usually affecting people between the ages of 10 and 30
• Chondrosarcoma, which forms in cartilage cells and rarely occurs in people under the age of 20
• Ewing tumor, also called Ewing’s sarcoma, which most frequently occurs in children and teenagers
• Fibrosarcoma and malignant fibrous histiocytoma, which usually develops in the soft tissue around the bones and tends to occur in older adults
• Giant cell tumor, which also includes benign tumors (noncancerous) and usually occurs in the arms or legs of young adults and middle-aged adults
• Chordoma, which affects bones in the spine and the base of the skull and occurs most frequently in adults 30 or older, particularly men
• Metastatic bone cancer, which spreads to other parts of the body but is still considered bone cancer

Not all bone tumors are malignant. Benign bone tumors include osteoid osteoma, osteoblastoma, osteochondroma, enchondroma and chondromyxoid fibroma.

Learn more about bone cancer types

Tools frequently used for bone cancer diagnosis include:

• Needle biopsy, performed with a local anesthetic to numb the injection area
• Surgical biopsy, typically performed under general anesthesia to remove a bone tissue sample (incisional biopsy) or a whole tumor (excisional biopsy)
• Radionuclide bone scan
• X-ray
• Magnetic resonance imaging (MRI)
• Computed tomography (CT) scan
• Positron emission tomography (PET) scan

Learn more about diagnostic procedures for bone cancer