Chapter 18 - Sarcoma

Summary

Sarcomas are solid malignant tumors arising from mesenchymal tissue with distinct clinical and pathological features. They constitute a diverse group of tumors with more than 50 different histological subtypes divided into two broad categories: sarcomas of soft tissues (including fat, muscles, nerves, blood vessels, and other connective tissues) and sarcomas of bones (1, 2). Several classification schemes for sarcoma exist. In general, classification is based on histology with tumors subdivided according to the presumed tissue of origin.

Sarcomas can occur anywhere in the body and at all ages in both men and women. The age of incidence depends, at least in part, on the type as well as the subtype. For example, osteosarcomas tend to develop in young adults while chondrosarcomas are more common in older patients. Sarcomas found within certain organs may be difficult to differentiate from other malignancies; therefore, the true incidence of sarcomas is likely underestimated (3). Collectively, sarcomas are believed to account for approximately 1% of all adult malignancies and 15% of all pediatric malignancies (1). While soft tissue sarcomas are overall more frequent in middle-aged and older adults than in children and young adults, some subtypes such as rhabdomyosarcoma and synovial sarcoma are more common in young patients. Indeed soft tissue sarcomas account for a large proportion of pediatric malignancies, i.e., 7–10%. The incidence of primary bone tumors is approximately one-fifth that of soft tissue sarcomas. However, primary bone tumors also represent a significant percentage of malignancies in patients under the age of 20. Sarcomas are an important cause of death in the 14–29 years age group (4). Even in adults, the number of years of life lost is substantial despite the very low incidence of the disease, because people are often affected during the prime of their life (3).