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Ewing Sarcoma - Stages and Types of Ewing Sarcoma

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Ewing sarcoma is a rare condition characterized by cancer cells in the bone, with or without affecting the surrounding soft tissues. The condition is highly aggressive and requires prompt diagnosis and management.

What Is Ewing Sarcoma?

It is a cancer of the bone and may or may not involve the surrounding soft tissues, such as nerves or cartilage. The common sites for this condition are the feet, arms, legs, pelvis, chest, hands, skull, and spine. Although Ewing sarcoma may occur at any age, it is relatively more common in children and adolescents. Ewing tumors should be diagnosed and treated early for better health outcomes.

Is Ewing Sarcoma Common?

Ewing sarcoma is a rare condition. It is the second most common cancer of the bone in children and adolescents. A study reported its prevalence as 2.9 cases per million in individuals between the ages of one and 19 years. Almost 80% of cases of Ewing tumor are reported in individuals below 18 years of age. The cases of Ewing tumors in adults over 40 years old are < 1%. There is a higher incidence of Ewing tumor in Caucasians than in Africans and Asians. In India, Ewing sarcoma accounts for almost 15% of all bone cancers. Males and females between the ages of 10 and 14 have incidence rates of 4.4 and 2.9 per million, respectively.

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What are the Types of Ewing Sarcoma?

Some of the types of Ewing sarcoma are:

Ewing's Sarcoma of Bone

It is the most common form of Ewing sarcoma and constitutes about 87% of the total wing sarcoma cases. This tumor was initially described by Dr. James Ewing, who reported that the cells of these tumors are different from osteosarcoma (another common bone tumor). Ewing's sarcoma of the bone is sensitive to radiation therapy.

Soft Tissue (Extraosseous Ewing) Tumor (EOE)

These are also known as extraskeletal Ewing sarcoma. It initiates in the soft tissues that surround the bones. The properties of malignant cells are similar to those of the Ewing sarcoma of the bones. However, the outcomes and patient characteristics of the EOE may differ from those of the Ewing sarcoma of the bones. The most common symptoms include pain and a growing mass.
The methods for diagnosing EOE include immunohistochemical tissue examination, histopathological examination, ultrasound, computed tomography, and magnetic resonance imaging. There are no specific imaging characteristics of the EOE. The condition may be confused with benign lesions. Although EOE is radiosensitive, radiation therapy-related side effects and advancements in surgical techniques limit the use of radiation therapy.

Peripheral Primitive Neuroectodermal Tumor (PNET)

These are aggressive malignancies commonly developed in the abdomen, pelvis, and thoracopulmonary region and less commonly in the neck and head. The tumors may originate in the bone or soft tissues at the affected site and have features similar to those of bone and EOE sarcoma. In the pelvic region, PNET generally occurs in the cervix, ovaries, uterine corpus, and vulva. Genetic studies and immunohistochemical profiles of the tumor assist pathologists in differentiating it from other small round-cell tumors.

Askin's Tumor

A peripheral primitive neuroectodermal tumor (PNET) in the thoracopulmonary region is known as Askin’s tumor. It usually occurs in the chest wall, especially in the paravertebral region. Diagnosis is challenging as it mimics various other pulmonary conditions, such as neuroblastoma, tuberculosis, lymphoma, and rhabdomyosarcoma. The patients are presented with pain, loss of weight, and dyspnea. The disease is highly aggressive, with a poor prognosis and a short survival period. As the condition is rare, there are no standard treatment guidelines. Usually, the oncologists follow a multimodal treatment approach that comprises surgery, radiation therapy, and chemotherapy.

What are the Ewing Sarcoma Stages?

Depending on the extent of the disease's spread, the following are the Ewing sarcoma stages:

TNM Stages

The American Joint Committee classifies Ewing sarcoma based on two classification systems. One classification is for bone cancer (Ewing sarcoma of the bone), and the other is for soft tissue sarcoma (EOE). The staging of Ewing tumors is done according to the TNMG system. It is based on tumor size and location, lymph node invasion, metastatic status, and tumor grade.

Stage 1

Stage 1 is generally not assigned to Ewing tumors, as they are considered to be of high grade. However, other bone cancers, assigned as grade 1, can be assigned stage 1.

Stage 2

Stage 2 is subdivided into stages 2A and 2B. In Stage 2A, the tumor is less than 8 cm, of high grade, and does not spread to lymph nodes and other organs. In stage 2B, the tumor is more than 8 cm, of high grade, and does not spread to lymph nodes and other organs.

Stage 3

In stage 3 Ewing sarcoma, the tumors are present at multiple sites on a single bone and are of high grade. The tumors do not spread to the lymph nodes or other organs.

Stage 4

Stage 4 Ewing sarcoma is subdivided into stages 4A and 4B. In stage 4A, the tumor is of any size and grade and spreads to the lungs and nearby lymph nodes. However, it does not spread to other organs. In stage 4B, the tumor is of any size and grade and does not spread to the lungs but to other organs. It may or may not have invaded the lymph nodes.

Conclusion

Ewing sarcoma is a rare cancer that begins in the bone and the soft tissues around the bones. The types of Ewing sarcoma include Ewing sarcoma of the bone, soft tissue (extraosseous Ewing) tumor, peripheral primitive neuroectodermal tumor, and Askin's tumor. The stages of Ewing tumors are defined based on both the bone cancer staging system and the soft tissue sarcoma system.

Frequently Asked Questions

Is Ewing sarcoma curable?

The success rates of Ewing sarcoma treatment depend on various factors, such as stage of diagnosis, response to treatment, other medical conditions, and patient age.

Ewing sarcoma is also known as Ewing tumor, Ewing sarcoma cancer, or Ewing sarcoma tumor. The types of Ewing sarcoma include Ewing sarcoma of the bone, soft tissue (extraosseous Ewing) tumor, peripheral primitive neuroectodermal tumor, and Askin's tumor.

Patients with Ewing tumors are presented with pain that usually gets worse at night or during exercise.

There is a significant variation in the growth of Ewing tumors based on individual characteristics and the type of Ewing tumor. However, it may have the potential to grow to a noticeable size in a few weeks or months.

The common sites for developing Ewing tumors are the feet, legs, arms, hands, chest, pelvis, skull, and spine.