The skeletal system is made up of bones and joints and provides support, mobility, and protection to various organs in the body. We are born with more than 300 bones. Many of them, such as the skull bones, fuse together and as an adult we have 206 bones. The largest bone in the human body is the femur (thigh bone) and the smallest bones in the human body are the three bones of the middle ear. Maximum bone growth occurs during childhood and puberty, and tapers off as the person approaches 16-18 years of age. While the bones do not grow in size after 18-20 years, they do not remain just as stagnant, hard and inert structures. Continuous metabolic processes called bone remodeling, during which bone is resorbed and formed again occur throughout our life. A major role in this process is played by specialized cells in the skeletal system called osteoblasts which are bone lining cells, and osteoclasts which are bone dissolving cells. Our entire skeleton is renewed every few years and it is estimated that at any time about 20% of an adult bone is undergoing remodeling.
Bone cancer is the cancer originating primarily from the bone and its surrounding tissue. However, the most common form of cancer in the bones is from metastasis from another primary cancer at a different organ. Osteosarcoma is the most common primary bone cancer followed by chondrosarcoma, Ewing’s sarcoma, fibrosarcoma and others.
Osteosarcoma is the most common type of bone cancer frequently occurring in children and young adults between the ages of 10 and 30. People over 60 are also at an increased risk. In the US, almost 800 new cases of osteosarcoma are diagnosed every year and more than 400 are in children and teens younger than 20. Initial symptoms of osteosarcoma, such as pain, bone or joint swelling, and decreased joint motion can be misleading and frequently occur in children due to sports and other injuries. In older adults, the symptoms can be misdiagnosed as arthritis.