Structural Biochemistry/Sarcoma

Definition
Sarcoma refers to the cancer that is derived from connective tissue that develop from cells that come from mesenchymal cells. Examples of tissue that this type of cancer arises include cartilage, bone, nerves, muscle, and fat tissues. Unlike carcinomas, sarcomas are rare.

Classification
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.[1] 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
There are several different types of Sarcoma that were identified:
 * Askin's tumor
 * Sarcoma botryoides
 * Chondrosarcoma
 * Ewing's
 * PNET
 * Malignant Hemangioendothelioma
 * Malignant Schwannoma

Soft tissue sarcomas, including:
 * Alveolar soft part sarcoma
 * Angiosarcoma
 * Cystosarcoma Phyllodes
 * Dermatofibrosarcoma protuberans (DFSP)
 * Desmoid Tumor
 * Desmoplastic small round cell tumor
 * Epithelioid Sarcoma
 * Extraskeletal chondrosarcoma
 * Extraskeletal osteosarcoma
 * Fibrosarcoma
 * Hemangiopericytoma (Also known as "solitary fibrous tumor". Only a subset of these tumors are classified as malignant.)
 * Hemangiosarcoma (More commonly referred to as "angiosarcoma")
 * Kaposi's sarcoma
 * Leiomyosarcoma
 * Liposarcoma
 * Lymphangiosarcoma
 * Malignant peripheral nerve sheath tumor
 * Neurofibrosarcoma
 * Rhabdomyosarcoma
 * Synovial sarcoma

Diagnosis
Typically sarcomas are diagnosed through the process of biopsy, in which the suspected tissues are extracted and examined by the pathologist. Fine needle aspiration, core needle, and surgical biopsy are all methods used to diagnose sarcoma. Imaging tests are also utilized before the biopsy in some scenarios, but is usually done once the diagnosis of the sarcoma is made. Methods of imaging tests include chest x-rays, computed tomography scans, magnetic resonance imaging scans, ultrasound, and positron emission tomography scans. Sarcomas typically originate within the arms or legs, and the physical characteristic shown is usually a lump that has appeared over a period of time.

Treatment
Surgery is the most significant treatment that is used for most sarcomas. Limb sparing surgery is used instead of amputation. Other treatments include chemotherapy and radiation therapy.

Epidemiology
Only 15,00 new cases of sarcomas occur per year within the United States, thus making sarcomas take part as around one percent of the 1.5 million new cancer diagnoses. The most common form of sarcoma is the gastrointestinal stromal tumor, which occurs at around 3000 cases per year in the U.S. Sarcomas also tend to affect people of all ages.