A risk factor is anything that affects your chance of getting a disease such as cancer. Lifestyle-related risks are the most significant factors contributing to cancers in adults. Examples include the effects of unhealthy diet (high-fat, low-fiber, etc.), not enough exercise, and habits such as smoking and drinking alcohol. Lifestyle-related risk factors have little or no significance to childhood cancer.

Age and Height

The risk of osteosarcoma is highest during the teenage "growth spurt." Children with osteosarcoma are usually tall for their age. This suggests a relationship between rapid bone growth and risk of tumor formation.

Radiation to Bones

People who were treated with radiation for another cancer have a higher risk of later developing post-radiation (after radiation) osteosarcoma. Being treated at a younger age and being treated with higher doses of radiation (doses of more than 60 Gray – typically about 30 treatments) both increase the risk of developing osteosarcoma. There is little if any danger of developing osteosarcoma from having diagnostic x-rays.

Certain Bone Diseases

Children and adolescents with certain non-cancerous bone diseases have an increased risk of later developing osteosarcoma, usually as an adult. Some of these diseases include Paget disease of bone and multiple hereditary osteochondromas.

Paget disease is a benign but precancerous condition that affects one or more bones. It mostly affects people older than 50. Paget disease causes abnormal bone tissue to form. Affected bones are heavy and thick but are weaker than normal bones and are more likely to break. Usually this condition by itself is not life-threatening. But bone sarcomas (usually osteosarcoma) develop in about 5% to 10% of people with severe cases of Paget disease, usually when many bones are affected.

Osteochondromas are benign bone tumors formed by bone and cartilage. Each osteochondroma has a very slight risk of developing into an osteosarcoma. Most osteochondromas are cured by surgery. However, some people inherit a tendency to develop many osteochondromas, and it may not be possible to remove them all. The more osteochondromas a person has, the greater the risk of developing osteosarcoma.

Inherited Cancer Syndromes

Children with certain rare, inherited cancer 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, adrenal gland cancer, osteosarcoma, and other types of cancer.

• Retinoblastoma is a rare eye cancer of children. About 40% of cases are due to an inherited tendency to develop this cancer. Children with this inherited form also have an increased risk for developing osteosarcoma. When children with retinoblastoma are treated with radiation therapy, it increases their risk of developing osteosarcoma in the bones of the skull.

The way in which inherited abnormalities of DNA make certain children likely to develop osteosarcoma is explained in the section, "Do We Know What Causes Osteosarcoma?" Last Revised: 03/19/2007