In 1921, Dr. James Ewing described a bone tumor in children that was different from the more common bone tumor, osteosarcoma. Its most important feature was that it could be treated with radiation. This new tumor became known as Ewing sarcoma or Ewing tumor. At first, this tumor was only seen in bones. Later, the same type of tumor was found in the soft tissues and named extraosseous (outside bone) Ewing (EOE). About 60% of Ewing tumors start in bone.

Another childhood cancer, primitive neuroectodermal tumor (PNET), shares many features with Ewing tumor and EOE. PNETs are rare cancers, also found in soft tissue and bone. Researchers have found that Ewing tumor, EOE, and PNET cells are very similar. They have the same abnormalities in their DNA and have similar proteins that are rarely found in other types of cancers. They also believe these 3 cancers develop from the same type of normal cells in the body. Although there are slight differences among these tumors, they are all treated in the same way.

Doctors now refer to this group of cancers as the Ewing family of tumors. This family of tumors can occur at any age, but these tumors are most common in early teenage years. About 15% occur in adults. Most of these tumors occur in the trunk, and the most common place is the pelvis. About one third of the bone tumors occurs in the legs, mainly in the middle of the long bones. In contrast, osteosarcoma usually occurs at the ends of the long bones, especially around the knees. The next most common sites are the ribs and spine. The extraosseous tumors can occur almost anywhere.

Revised: 06/19/2006