Childhood bone cancer is a cancerous, or malignant, tumour that starts in bone or cartilage cells. Cancerous means that it can invade, or grow into, and destroy nearby tissue. It can also spread, or metastasize, to other parts of the body. When cancer starts in bone or cartilage cells, it is called primary bone cancer. Childhood bone cancer is rare. Non-cancerous, or benign, conditions of the bone are more common. Non-cancerous conditions of the bone such as bone cysts, pathological fractures and even infections can have the same symptoms as a childhood bone cancer. The most common type of bone cancer in children is osteosarcoma. It starts in bone cells and occurs most often during the adolescent growth spurt. It commonly starts in the end of a long bone.

Information taken from https://www.cancer.ca/en/cancer-information/cancer-type/bone-childhood/childhood-bone-cancer/?region=on