Risk Factors

A risk factor is anything that increases a person’s chance of developing cancer. Some risk factors can be controlled, such as smoking, and some cannot be controlled, such as age and family history. Although risk factors can influence the development of cancer, most do not directly cause cancer. Some people with several risk factors never develop cancer, while others with no known risk factors do.

Most osteosarcoma arises sporadically. That is, it appears in people with no other diseases and with no family history of bone cancer.

Osteosarcoma may be triggered by overactive bone cells. The possibility of changes in genes that can lead to this overactivity is being studied in a small number of families where siblings have developed osteosarcoma. Such changes, while very uncommon, may help doctors better understand the development of osteosarcoma in people with no family history of the disease, since similar genetic changes may occur in their cancer cells.

Osteosarcoma is probably caused by a combination of genetic changes that together cause immature bone cells to become cancer cells instead of developing into bone. The same gene (called the RB gene) that is commonly abnormal in children with a rare type of eye cancer called retinoblastoma may also be associated with osteosarcoma. RB is a tumor suppressor gene that normally controls the growth of cells. When it is mutated (changed), it can no longer control cell growth, and a tumor can form. In addition, many other changes occur in the genes of osteosarcoma cells.

There are several groups that have higher rates of osteosarcoma than the rest of the population.

• Teenagers who are having a growth spurt have the highest incidence of osteosarcoma. Researchers are looking for a link between rapid bone growth and tumor development.
  
  
• People who have received radiation treatment for other types of cancer are more likely to develop osteosarcoma. Also, higher doses of radiation treatment at a younger age increase the risk.
  
  
• Children with an inherited form of retinoblastoma are more likely to develop osteosarcoma.
  
  
• Children with Li-Fraumeni syndrome (a rare disorder of a gene, p53, that is responsible for eliminating abnormal cells) have a higher risk, not only of sarcoma, but also brain and breast cancers.

People with Rothmund-Thomson syndrome, an uncommon disorder characterized by short stature, rash, alopecia (hair loss), and skeletal dysplasia (noncancerous abnormalities of the bones) are more likely to develop osteosarcoma.