Osteosarcoma primarily develops in the bones, states the American Cancer Society. It is the most prevalent type of bone cancer, commonly affecting children, teenagers and young adults.
Osteosarcoma specifically arises from the osteoblast cells that produce new bone. Although this type of malignancy can form in any bone in the body, osteosarcoma frequently occurs in the long bones surrounding the knees, notes Johns Hopkins Medicine. It can also develop in the bones of the upper and lower limbs, as well as in the bones of the pelvis, shoulder and head.
Osteosarcoma can also migrate to other sites in the body. Cancerous cells can affect the surrounding tendons and muscles or enter the bloodstream and spread to other organs and bones.