Childhood bone cancer is a malignant tumour that starts in bone or cartilage cells. Malignant means that it can spread, or metastasize, to other parts of the body. When cancer starts in bone or cartilage cells, it is called primary bone cancer.
Together, groups of bones and cartilages form the skeleton. Bones protect the organs inside the body and give it structure and support. Cartilage covers the ends of bones. It stops bones from rubbing together and acts like a cushion.
Bone or cartilage cells sometimes change and no longer grow or behave normally. These changes may lead to benign bone conditions such as cysts. They can also lead to benign tumours such as osteochondroma. Benign conditions and tumours are not cancerous. But in some cases, changes to bone or cartilage cells cause bone cancer.
The most common type of bone cancer in children is osteosarcoma. It starts in bone cells. Almost half of all childhood bone cancers are osteosarcoma. It occurs most often during the adolescent growth spurt. It commonly starts in the end part of the long bones. The second most common type of childhood bone cancer is called Ewing sarcoma. It usually begins in the pelvis, breastbone (also called the sternum), ribs, spine or skull. These tumours can also develop in the middle part of long bones in the arms or legs. In some cases they develop in soft tissues of the body rather than in bones.
Other types of cancer can spread to the bones, but this is not the same disease as primary bone cancer. Cancer that starts in another part of the body and spreads to the bone is called bone metastasis. It is not treated in the same way as primary bone cancer. Find out more about bone metastasis.