Ewing Sarcoma

Ewing sarcoma is the second most common type of bone tumour to affect children, after osteosarcoma.

Whilst almost all cases of osteosarcoma occur in either the long bones of the legs (the femur and tibia) or the long bone of the arms (the humerus), Ewing sarcoma occurs in a broader range of sites.

Ewing sarcoma is actually a group of four different types of cancer, known collectively as the Ewing family of tumours (EFT). Ewing sarcoma of bone is the most common of these. Extraosseous Ewing sarcoma occurs in the soft tissue surrounding bone; peripheral primitive neuroectodermal tumour (PNET) can be found in either the bone or the soft tissue and Askin tumour occurs in the chest wall.

The cause of EFTs is unknown but it is thought that they may be linked to periods of rapid bone growth, explaining why they are seen more often in teenagers.

Incidence

Ewing tumours of bone account for 37 per cent of the bone tumours occurring in children. Up to 25 children per year are diagnosed in the UK.

Up to 40 per cent of childhood Ewing sarcomas occur in the femur and tibia. Substantial numbers of cases arise in the pelvis (23 per cent), long bones of the arms (11 per cent), ribs, sternum and clavicle (9 per cent) and spinal column (8 per cent).

Ewing sarcoma has a lower incidence in children than osteosarcoma. The majority of cases are in the 10 to 14 year age group but the predominance of older children is less pronounced than for osteosarcoma. Up to the age of 6 years, Ewing sarcoma is the most common type of malignant bone tumour.

Incidence is similar in boys and girls up to age 10 when a male excess begins to emerge. This male excess emerges later in osteosarcoma (around 15 to 16 years).

In addition to the Ewing tumours of bone, around 16 children a year are diagnosed with the soft tissue types of Ewing sarcoma.

Survival

The overall five year survival rate for Ewing sarcoma of bone is 68 per cent. For extraosseous tumours, the survival rate is lower at 58 per cent.

An individual’s prognosis depends on the size of the tumour, site, whether it has spread and response to treatment.

The following symptoms of Ewing Sarcoma may be noted:

• Bone pain – this may come and go initially but then become more persistent
• Tenderness
• Redness
• Swelling
• Fracture may occur after a minor injury at the site of the weakened bone

The doctor may arrange an initial X-ray, and then refer to a cancer specialist who will usually perform a biopsy under anaesthetic (a sample of the affected bone is taken for examination under the microscope), blood tests and scans (bone scan, CT or MRI).

These tests will enable doctors to confirm the diagnosis and to determine the size of the size of the tumour and whether it has spread. This is known as staging. Knowing the stage of the cancer helps doctors decide on the most appropriate treatment. Ewing sarcomas are divided into two groups: localized tumours are found in only one part of the body; metastatic tumours have spread to other parts of the body.

Treatment of Ewing Sarcoma varies according to the size, stage and position of the tumour. However it may include a combination of surgery, chemotherapy and radiotherapy.

1. A number of different chemotherapy drugs are given. They are usually given before surgery to kill the cancer cells and shrink the tumour and continue after surgery to destroy any remaining cancer cells and prevent recurrence (relapse).
2. The extent of surgery will depend on the site and size of the tumour. Often the tumour can be removed without causing too much damage, however if the tumour is in one of the main bones of the arm or leg, the affected limb may need to be amputated. If only part of the affected bone is removed, this is known as limb-sparing surgery.If amputation is unavoidable, a false limb will be fitted and a programme of rehabilitation will help the child to resume normal activities.Limb-sparing surgery involves either replacing the bone with an artificial prosthesis or replacing it with bone taken from another part of the body.
3. Radiotherapy has shown to be very effective in the treatment of Ewing sarcoma and is often used after chemotherapy and before or after surgery. Sometimes it may be used in place of surgery if surgery is not possible.

Side effects and complications

In the short-term, treatment of Ewing Sarcoma can cause side effects such as pain, tiredness, nausea, vomiting, infections, hair loss, bruising, and tiredness.

In the longer-term, late effects of treatment, which can occur months or years later, can include abnormal bone growth, heart or lung effects, infertility and an increased risk of developing another cancer. There may be psychological problems associated with having a false limb, as well as the obvious physical limitations.

Follow-up

The child will have regular follow-ups to check for any recurrence of the cancer and for any problems that may arise as a result of the treatment they were given (late effects).

They will be checked up on every few months for the first three years after treatment and then every six months for another two years.

If the tumour comes back, further treatment may be given successfully.

Many children have their treatment as part of a clinical trial.

Trials aim to improve our understanding of the best way to treat the cancer, usually by comparing the standard treatment with a new or modified version.

If appropriate, the child’s medical team will discuss participation in a relevant trial. Participation is optional but may offer the opportunity to receive new treatments.

Children with Cancer UK is funding a number of research projects focused on bone tumours.

Further information

More detailed information about Ewing sarcoma in children and its treatment is available from Macmillan Cancer Support