Sarcoma

A sarcoma (from the Greek sarx meaning "flesh") is a cancer that arises from transformed cells in one of a number of tissues that develop from embryonic mesoderm. Thus, sarcomas include tumors of bone, cartilage, fat, muscle, vascular, and hematopoietic tissues. (This is in contrast to carcinomas, which originate from epithelial cells and thus give rise to more common malignancies, such as breast, colon, and lung cancer.)

Tissue
Sarcomas are given a number of different names, based on the type of tissue from which they arise. For example, osteosarcoma arises from bone, chondrosarcoma arises from cartilage, liposarcoma arises from fat, and leiomyosarcoma arises from smooth muscle.

Grade
In addition to being named based on the tissue of origin, sarcomas are also assigned a grade (low, intermediate, or high) based on the presence and frequency of certain cellular and subcellular characteristics associated with malignant biological behavior. Low grade sarcomas are usually treated surgically, although sometimes radiation therapy or chemotherapy are used. Intermediate and high grade sarcomas are more frequently treated with a combination of surgery, chemotherapy and/or radiation therapy. Since higher grade tumors are more likely to undergo metastasis (invasion and spread to locoregional and distant sites), they are treated more aggressively. The recognition that many sarcomas are sensitive to chemotherapy has dramatically improved the survival of patients. For example, in the era before chemotherapy, long term survival for patients with localized osteosarcoma was only approximately 20%, but now has risen to 60-70%.

Types
(ICD-O codes are provided where available.)
 * Askin's Tumor (8803/3)
 * Botryodies
 * Chondrosarcoma (9220/3-9240/3)
 * Ewing's (9260/3) - PNET (9473/3)
 * Malignant Hemangioendothelioma (9130/3)
 * Malignant Schwannoma (9560/3-9561/3)
 * Osteosarcoma (9180/3-9190/3)
 * Soft tissue sarcomas, including:
 * Alveolar soft part sarcoma (9581/3)
 * Angiosarcoma (9120/3)
 * Cystosarcoma Phyllodes
 * Dermatofibrosarcoma protuberans (DFSP) (8832/3-8833/3)
 * Desmoid Tumor (8821/1-8822/1)
 * Desmoplastic small round cell tumor (8806/3)
 * Epithelioid Sarcoma (8804/3)
 * Extraskeletal chondrosarcoma (9220/3)
 * Extraskeletal osteosarcoma (9180/3)
 * Fibrosarcoma (8810/3)
 * Hemangiopericytoma (9150)(Also known as "solitary fibrous tumor". Only a subset of these tumors are classified as malignant.)
 * Hemangiosarcoma (9120/3) (More commonly referred to as "angiosarcoma")
 * Kaposi's sarcoma (9140/3)
 * Leiomyosarcoma (8890/3-8896/3)
 * Liposarcoma (8850/3-8858/3)
 * Lymphangiosarcoma (9170-9175)
 * Lymphosarcoma (Not considered to be sarcomas)
 * Malignant fibrous histiocytoma (8830/3)(This is an obsolete term that is no longer recognized by the World Health Organization. Many of these tumors would currently be classified as "undifferentiated pleomorphic sarcoma".)
 * Malignant peripheral nerve sheath tumor (MPNST)
 * Neurofibrosarcoma (9540/3)
 * Rhabdomyosarcoma (8900-8920)
 * Synovial sarcoma (9040/3-9043/3)
 * Undifferentiated pleomorphic sarcoma (previously referred to as Malignant fibrous histiocytoma)

Treatment

 * Liposarcoma treatment consists of surgical resection, with chemotherapy not being used outside of the experimental setting. Adjuvant radiotherapy may also be used after surgical excision for liposarcoma.
 * Rhabdomyosarcoma is treated with surgery, radiotherapy, and/or chemotherapy. Five-year survival is 50% for most rhabdomyosarcoma patients.
 * Osteosarcoma is treated with surgical resection of as much of the cancer as possible, often along with neoadjuvant chemotherapy. Radiotherapy is a second alternative although not as successful.

Epidemiology
Sarcomas are quite rare with only 15,000 new cases per year in the United States. Sarcomas therefore represent about one percent of the 1.5 million new cancer diagnoses in that country each year, and are well below the US's orphan disease threshold of 200,000 cases per year.

Gastrointestinal stromal tumor (GIST) is the most common form of sarcoma, with approximately 3,000-3,500 cases per year in the United States.

Sarcomas affect people of all ages. Approximately 50% of bone sarcomas and 20% of soft tissue sarcomas are diagnosed in people under the age of 35. Some sarcomas, such as leiomyosarcoma, chondrosarcoma, and gastrointestinal stromal tumor (GIST), are more common in adults than in children. Most high-grade bone sarcomas, including Ewing's sarcoma and osteosarcoma, are much more common in children and young adults.