SARCOMA

tumour of connective tissue (also called mesodermal, or mesenchymal, cells). This form of cancer is relatively rare in adults but is one of the more common malignancies among children; it often spreads to other tissues in the body. Sarcomas are generally divided into bone and soft-tissue tumours, the latter being much less common. Because mesenchymal cells form a variety of mature tissues, tumours may have the characteristics of bone (osteosarcoma), cartilage (chondrosarcoma), muscle (myosarcoma), or blood vessels (angiosarcoma). The varieties overlap, and the name given to the sarcoma is taken from that of the most developed tissue contained within the tumour. The most common is osteosarcoma; this malignancy of immature bone (osteoid) was highly lethal before the use of anticancer drugs, which have increased the survival rate to about 90 percent. Specific chromosomal abnormalities are associated with some sarcomas. See also bone lesion.