Sarcomas are cancers of the body's scaffolding: bone, muscle, fat and vessels
Carcinomas are far more common, but sarcomas grow from connective tissue such as bone, cartilage, muscle and fat. They account for only about 1% of adult cancer diagnoses yet roughly 15% of childhood ones, and chemotherapy has transformed the outlook for young patients with bone tumours.
Greek gave the disease its label: a term for a fleshy lump, built on sarx, flesh. Sarcomas form one of five cancer types sorted by the cell they come from, in this case mesenchymal cells. Doctors split them into bone and soft-tissue groups, each with many subtypes such as liposarcoma, leiomyosarcoma and osteosarcoma. A true sarcoma starts in connective tissue, unlike a tumour that has travelled there from, say, the lung or breast.
Bone sarcomas typically cause pain, often worse at night, plus swelling. Soft-tissue sarcomas tend to appear as firm lumps that may not hurt. Most arise from random mutations, but known risks include earlier radiation treatment, with sarcomas appearing 10 to 20 years later, certain chemotherapy drugs, inherited conditions such as Li-Fraumeni syndrome and, for angiosarcoma, exposure to vinyl chloride fumes or arsenic. Kaposi sarcoma is caused by a herpesvirus, HHV-8.
Some subtypes carry a genetic signature. In most Ewing sarcomas, pieces of chromosomes 11 and 22 swap places, fusing the EWSR1 gene to FLI1 in 90% of cases, and many liposarcomas carry extra copies of part of chromosome 12, boosting growth genes such as MDM2. Blood tests help little in diagnosis; imaging comes first, but only a biopsy read by an experienced pathologist confirms the disease. Tumours are graded low, intermediate or high according to how aggressive the cells look.
Surgery is the only cure for most sarcomas that have not spread, and limb-sparing operations now avoid amputation in at least 90% of arm and leg cases. Chemotherapy or radiotherapy before or after the operation improves many patients' prospects, though treatment often lasts about a year. For children with localised osteosarcoma, long-term survival rose from about 20% before chemotherapy to 60–70%. As of March 2019 neither the US Preventive Services Task Force nor the American Cancer Society recommended routine screening, likely because the disease is so rare.
Source: Sarcoma
