Osteosarcoma is the most common type of primary bone cancer. Approximately 900 new cases of osteosarcoma are diagnosed each year in the United States. The presentation of this disease is bimodal, with peaks in adolescence and after the age of 50 years. The tumors typically arise in the metaphyseal regions of long bones, with the distal femur, proximal tibia, and proximal humerus representing the three most common sites. Genomic amplification, especially of both the p53-binding MDM2 gene and the flanking SAS gene, plays an important role in the biology of these tumors. Alterations of Rb1 and c-myc are also common, and mutations have been reported in p53, p16INK4A, and CDKN2B.
