Bone cancer is the abnormal growth of cells that begins in the bone. While it can start in any bone in the body, it most commonly affects the thighbone (femur).

The term bone cancer refers specifically to cancer that originates in the bones. It does not include cancers that begin in other parts of the body and then spread to the bones. When cancer spreads to the bone from another area, for example, the lungs, it is still called by the name of the original cancer. In that case, it would be referred to as lung cancer that has metastasized to the bones.

Primary bone cancer (cancer that starts in the bone) is rare. There are several types, some of which are more common in children, while others tend to occur in adults.