Cancer that is discovered in bones can either represent cancer which has spread from a distant site (i.e., breast, prostate, lung) or can be a cancer which originates in bone (sarcoma). Cancers which spread to bone represent 98% of all bone cancers. Cancers that start in the bone are rare. Only about 2,000 new cases of primary bone cancers (as opposed to cancers that spread to the bone from other areas) are diagnosed in the United States each year. Approximately 5,000 to 6,000 new cancers in the soft tissues of the body are diagnosed annually.

Primary bone cancers (sarcomas) tend to be more common in children and adolescents than in adults. Most adults with a bone cancer have cancer that has spread to the bone from its primary site, such as the breast, lung or prostate. Less commonly, the bone cancer will have actually originated from the bone itself.