A risk factor is anything that affects your chance of getting a disease such as cancer. Different cancers have different risk factors. For example, exposing skin to strong sunlight is a risk factor for skin cancer. Smoking is a risk factor for cancers of the lung, mouth, larynx, bladder, kidney, and several other organs. But having a risk factor, or even several, does not mean that you will get the disease. Most people with bone cancers do not have any apparent risk factors.

Genetic disorders

A very small number of bone cancers (especially osteosarcomas) appear to be hereditary.

Osteosarcoma

Children with certain rare inherited syndromes have an increased risk of developing osteosarcoma.

• The Li-Fraumeni syndrome makes people much more likely to develop several types of cancer, including breast cancer, brain cancer, osteosarcoma, and other types of sarcoma. Most of those cases are caused by a mutation of the p53 tumor suppressor gene, but some are caused by mutations in the gene CHEK2.

• Another syndrome that includes bone cancer is the Rothmund-Thompson syndrome. Children with this syndrome are short, have skeletal problems, and rashes. They also are more likely to develop osteosarcoma. This syndrome is caused by abnormal changes in the gene REQL4.

• Retinoblastoma is a rare eye cancer of children that can be hereditary. The inherited form of retinoblastoma is caused by a mutation (abnormal copy) of the RB1 gene. Those with this mutation also have an increased risk of developing bone or soft tissue sarcomas. Also, if radiation therapy is used to treat the retinoblastoma, the risk of osteosarcoma in the bones around the eye is even higher.

Finally, there are families with several members that have developed osteosarcoma without inherited changes in any of the known genes. The gene defects that may cause cancers in these families haven't been discovered yet.

Chondrosarcoma

Multiple exostoses (sometimes called multiple osteochondromas) is an inherited condition that causes many bumps on a person's bones. These bumps are made mostly of cartilage. They can be painful and cause bones to deform and/or fracture. This disorder is caused by a mutation in any one of the 3 genes EXT1, EXT2, or EXT3. Patients with this condition have an increased risk of chondrosarcoma.

Paget disease

Paget disease is a benign (non-cancerous) but precancerous condition that affects one or more bones. It results in formation of abnormal bone tissue and is mostly a disease of people older than 50. Affected bones are heavy, thick, and brittle. They are weaker than normal bones and more likely to fracture (break). Most of the time Paget disease is not life threatening. Bone cancer (usually osteosarcoma) develops in about 1% of those with Paget disease, usually when many bones are affected.

Multiple enchondromatosis

An enchondroma is a benign cartilage tumor. People who get many of these tumors have a condition called multiple enchondromatosis. They have an increased risk of developing chondrosarcoma.

Radiation

Bone exposure to radiation may also increase the risk of developing bone cancer. A typical x-ray of a bone is not dangerous, but exposure to large doses of radiation does pose a risk. For example, radiation therapy to treat cancer can cause a new cancer to develop in one of the bones in the treatment area. Being treated at a younger age and/or being treated with higher doses of radiation (usually over 60 Gy) increases the risk of developing bone cancer. Exposure to radioactive materials such as radium and strontium can also cause bone cancer because these minerals build up in bones. Non-ionizing radiation, such as microwaves, electromagnetic fields from power lines, cellular phones, and household appliances, does not increase bone cancer risk.

Bone marrow transplantation

Osteosarcoma has been reported in a few patients who have undergone bone marrow (stem cell) transplantation.

Injuries

People have wondered whether injury to a bone can cause cancer, but this has never been proven. Many people with bone cancer remember having hurt that part of their bone. Most doctors believe that this did not cause the cancer, but that the cancer caused them to remember the incident, or that the injury drew their attention to that bone and caused them to notice a problem that had already been present for some time.