What Is the Ewing Family of Tumors?
Cancer starts when cells in the body begin to grow out of control. Cells in nearly any part of the body can become cancer, and can spread to other areas of the body. To learn more about how cancers start and spread, see What Is Cancer? For information about the differences between childhood cancers and adult cancers, see Cancer in Children.
The Ewing family of tumors is a group of cancers that start in the bones or nearby soft tissues that share some common features. These tumors can develop at any age, but they are most common in the early teen years.
The main types of Ewing tumors are:
- Ewing sarcoma of bone: Ewing sarcoma that starts in a bone is the most common tumor in this family. This type of tumor was first described by Dr. James Ewing in 1921, who found it was different from the more common bone tumor, osteosarcoma. Seen under a microscope, its cells looked different from osteosarcoma cells. It was also more likely to respond to radiation therapy.
- Extraosseous Ewing tumor (EOE): Extraosseous Ewing tumors start in soft tissues around bones, but they look and act very much like Ewing sarcomas in bones. They are also known as extraskeletal Ewing sarcomas.
- Peripheral primitive neuroectodermal tumor (PPNET): This rare childhood cancer also starts in bone or soft tissue and shares many features with Ewing sarcoma of bone and EOE. Peripheral PNETs that start in the chest wall are known as Askin tumors. (Peripheral PNETs are similar to, but not quite the same as, PNETs of the brain and spinal cord. For more information on those tumors, see Brain and Spinal Cord Tumors in Children.)
Researchers have found that the cells that make up Ewing sarcoma, EOE, and PPNET are very similar. They tend to have the same DNA (gene) abnormalities and share similar proteins, which are rarely found in other types of cancers. That’s why these 3 cancers are thought to develop from the same type of cells in the body. There are slight differences among these tumors, but they all get the same treatment.
Most Ewing tumors occur in the bones. The most common sites are:
- The pelvis (hip bones)
- The chest wall (such as the ribs or shoulder blades)
- 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. Extraosseous Ewing tumors can occur almost anywhere.
Most Ewing tumors occur in children and teens, but they can also occur in adults. This document focuses on the Ewing family of tumors in children and teens, but most of the information here (including much of the treatment information) applies to Ewing tumors in adults as well.
Other types of bone cancers
Several other types of cancers can start in the bones.
Osteosarcomas are the most common bone cancer in children and teens. They are described in Osteosarcoma.
Most other types of bone cancers are usually found in adults and are rare in children. These include:
- Chondrosarcoma (cancer that develops from cartilage)
- Malignant fibrous histiocytoma
- Malignant giant cell tumor of bone
For more information on these cancers, see Bone Cancer.
Many types of cancer that start in other organs of the body can spread to the bones. These are sometimes referred to as metastatic bone cancers, but they are not true bone cancers. For example, if a rhabdomyosarcoma (a cancer that starts in muscle cells) spreads to the bones, it is still rhabdomyosarcoma and is treated like rhabdomyosarcoma. For more information, see Bone Metastasis.
The rest of this document refers only to Ewing tumors.
Last Medical Review: September 18, 2014 Last Revised: February 4, 2016