Sarcoma

A sarcoma is a cancer of mesenchymal cells, the cells that build the body's connective and supporting tissues. That sets it apart from a carcinoma, the far more common cancer of the epithelial cells that line surfaces and form glands. Sarcomas are divided into bone sarcomas and soft tissue sarcomas, and they are named after the tissue they resemble: osteosarcoma (bone), chondrosarcoma (cartilage), liposarcoma (fat), leiomyosarcoma (smooth muscle), rhabdomyosarcoma (skeletal muscle) and angiosarcoma (blood vessels). There are dozens of subtypes.

Sarcomas are rare, making up a small fraction of adult cancers but a larger share of cancers in children and young adults, among whom osteosarcoma, Ewing sarcoma and rhabdomyosarcoma are typical. Most have no known cause, but the risk rises after radiation therapy, with exposure to certain chemicals and in some inherited syndromes, such as Li-Fraumeni syndrome caused by TP53 mutations. Kaposi sarcoma, linked to a herpesvirus, mainly affects people with weakened immunity. Soft tissue sarcomas usually appear as a growing lump, often painless, in a limb or the abdomen; bone sarcomas cause pain and swelling.

Sarcomas tend to spread through the bloodstream, most often to the lungs. Diagnosis relies on imaging and a biopsy read by a specialist pathologist, and treatment centers on removing the tumor with a margin of healthy tissue, often with radiation or chemotherapy.