Definition and Overview
Ewing’s sarcoma is a rare blue cell tumour commonly found in the bone or soft tissue. In bone, it most often develops in the spine, arm, rib, leg or pelvis. In soft tissue (soft tissue sarcoma), it typically occurs in the thigh, foot, and chest wall. The condition, which is commonly diagnosed in patients between ages 10 and 20 years old, was named after James R. Ewing, a pathologist and oncologist who described the first cases of the condition in 1921.
Although very rare (only about 225 cases are recorded in the United States every year), Ewing sarcoma is the second most common type of bone cancer in children. It follows rhabdomyosarcoma and it is highly curable. It does not appear to be inherited but evidence shows that it could develop due to exposure to radiation for cancer treatment.
The tumour is more common among Caucasians and is one of the three main types of bone cancer along with osteosarcoma and chondrosarcoma. In its advanced stages, it can spread to other areas of the body including the adrenal gland, heart, kidneys, bone marrow, and lungs.
Other than Ewing sarcoma of bone and extraosseous Ewing tumour (soft tissues tumours), the other type of this condition is called peripheral primitive neuroectodermal tumour (PPNET), another rare childhood cancer that starts in the chest wall. Research shows that the cells that make up these three types of Ewing’s tumour share similar proteins and DNA abnormalities that are rarely found in other types of cancer. For this reason, they are treated the same way.
Causes of the Condition
It remains unclear as to why Ewing’s sarcoma develops. However, research has confirmed that it is not hereditary and that the changes in the cell DNA responsible for Ewing sarcoma occur after birth. The genetic changes take place for no known reason.
A closer study of Ewing sarcoma cells reveals that small pieces of their genetic material swap places inside the tumour cell. Called chromosomal translocation, the process usually occurs between chromosomes 11 and 12 although it can also occur between chromosomes 17 and 22, 7 and 22, and 21 and 22. This leads to the uncontrollable growth of Ewing sarcoma cells.
Meanwhile, risk factors for this condition include the following:
Age – More than 50% of cases involve patients between the ages of 10 and 20.
Race/ethnicity – The condition occurs most frequently in Caucasians.
Gender – It is more common among boys than girls.
Cancer treatment – Some studies suggest that Ewing’s sarcoma could be a secondary cancer in patients who have been treated with radiation for another type of cancer.
Although Ewing’s sarcoma causes various symptoms, it is often not recognised right away as its signs can be easily confused with bruises, bumps, and even sports-related injuries. It is not uncommon for patients to get misdiagnosed and to be sent home with pain relievers and antibiotics if an infection was suspected. Most patients return to their doctor when signs and symptoms get worse and this is typically when they undergo various tests including bone x-rays.
Patients suffering from Ewing’s sarcoma typically observe the following:
Bone pain, which can be caused by a fracture or the spread of tumour under the periosteum (outer covering of the bone). The pain is typically worse at night.
Swelling usually in the legs or arms
Weakened bone causing patients to fall easily
Who to See and Types of Treatments Available
Ewing sarcoma is diagnosed using a variety of tests including blood tests and x-rays for both the chest and the painful part of the bone. Other tests, which include a bone scan, computed tomography (CT) scan, magnetic resonance imaging (MRI), and PET scan may also be performed.
Sarcoma cancer treatment is determined based on a number of factors including but not limited to:
The patient’s overall health condition and age
The severity of the condition (extent)
The patient’s tolerance to specific medical treatments
Surgical procedure for the removal of a bone tumour is performed in a hospital or a specialist orthopaedic bone tumour centre. The goal of the procedure is to remove the tumour without damaging nearby bones and soft tissue. However, in many cases, a part of the affected bone has to be removed to ensure that no cancer cells remain. If only a small part of the bone is removed, the procedure is referred to as limb-sparing surgery. In cases wherein the cancer has spread to surrounding nerves and blood vessels, the surgeon will perform an amputation. This is followed by prosthesis fitting and training to help the patient live a normal life as much as possible. They also usually undergo physical and occupational therapy after their surgery.
Surgery is often followed by adjuvant therapy, which could be either chemotherapy or radiotherapy to kill remaining cancer cells.
It is important for children and their parents to be informed of the possible complications of such treatment. These include hair loss, increased risk of infection, reduced infertility, reduction in normal bone growth, and an increased risk of developing another type of cancer in the future. However, it is important to note that new methods are continually being discovered and many of them have already improved treatment outcomes and decreased side effects.
The patients’ chances of survival depend on many factors but about 70% of diagnosed patients are able to make a complete recovery. However, patients between the ages of 15 and 19 have a lower Ewing’s sarcoma survival rate of about 56% while those whose cancer has already spread to other organs have 30% chance of survival. Children with tumours that are located in the spine, ribs, and pelvis are less likely to be cured.
It is important to note that Ewing’s sarcoma prognosis and long-term survival vary greatly from one patient to another. Patients have the best chances of surviving their condition with aggressive therapy and prompt medical attention.
Le Deley MC, Delattre O, Schaefer KL, et al. Impact of EWS-ETS fusion type on disease progression in Ewing's sarcoma/peripheral primitive neuroectodermal tumor: prospective results from the cooperative Euro-E.W.I.N.G. 99 trial. J Clin Oncol. 2010 Apr 20. 28(12):1982-8.
Leavey PJ, Mascarenhas L, Marina N, et al. Prognostic factors for patients with Ewing sarcoma (EWS) at first recurrence following multi-modality therapy: A report from the Children's Oncology Group. Pediatr Blood Cancer. 2008 Sep. 51(3):334-8.