Causes of Ewing’s sarcoma

The exact causes of primary bone cancer are unknown. The development of Ewing’s sarcoma may be in some way related to times of rapid bone growth, which may explain why more cases of Ewing’s sarcoma are seen in teenagers. Research is taking place to find out more about what may cause Ewing’s sarcomas.

Signs and symptoms

Pain is the most common symptom of bone cancer. However, symptoms may vary depending on the position in the body and the size of the cancer. There may be some swelling in the affected area and it may become tender to touch. Bone cancer is sometimes discovered when a bone that has been weakened by cancer breaks after the person has had a minor fall or accident.

Many of the symptoms described above are common to conditions other than cancer. However any persistent bone pain, especially if it occurs at night, should be checked by your doctor.

How it is diagnosed

Usually you begin by seeing your family doctor (GP), who will examine you and may arrange any tests or X-rays, which may be necessary. Your GP will probably refer you to a specialist surgeon (called an orthopaedic surgeon) who can carry out tests, to decide if you need a referral to a specialist hospital or bone tumour centre for further investigations. Many of the specific tests for diagnosing bone tumours, such as the biopsy, require experience and specialist technique.

The doctor at the hospital will take your full medical history before doing a physical examination. This will include an examination of the painful bone to check for any swelling or tenderness. You will probably have a blood test done to check your general health.

Further tests

Bone x-ray

This involves the use of x-rays to show the structure of the bone.

MRI (magnetic resonance imaging) scan

This is a specialist scan that uses magnetism to build up cross-sectional pictures of your body. Some people are given an injection of dye into a vein in the arm to improve the image.

During the test you will be asked to lie very still on a couch inside a long chamber for up to an hour. This can be unpleasant if you don’t like enclosed spaces, so it may help to mention this to the doctor working the machine. The machine is also very noisy and you will be given earplugs or headphones to wear.

Needle biopsy

For this test a small sample of the tumour is taken from the affected bone. The doctor looks at the sample under a microscope to identify the exact type of tumour that you may have.

Open biopsy

This type of biopsy is not often used, as the needle biopsy is much quicker and simpler. In an open biopsy a small piece of bone is removed during a minor operation while you are under a general anaesthetic. It may be necessary to do this if a needle biopsy can’t be done or doesn’t give a clear diagnosis.

Bone scan

This is a more sensitive test than the simple x-ray and shows up any abnormal areas of bone more clearly. For this test, a small amount of a mildly radioactive substance is injected into a vein, usually in your arm. Abnormal bone absorbs more radioactivity than normal bone so these areas are highlighted and picked up by the scanner as `hot spots’.

CT (computerised tomography) scan 

A CT scan is a specialised type of x-ray. A number of pictures are taken from different angles and fed into a computer to build up detailed pictures of structures within the body. A CT scan can show if the cancer has spread to other parts of the body. The scan is painless and takes 10–30 minutes.

Bone marrow sample

The bone marrow is the spongy material inside the bones, where our blood cells are made. Ewing’s sarcomas can sometimes spread to the bone marrow. When Ewing’s sarcoma has been diagnosed or is suspected, a small sample of bone marrow is taken from the hip bone (pelvis) and looked at under a microscope to see if it contains any abnormal cells. The bone marrow sample may be taken under a local anaesthetic, but in younger children it is usually done under a general anaesthetic.

Chest x-ray

In Ewing’s sarcoma the cancer may spread to the lungs. A chest x-ray is usually done to check if the cancer has spread.

Grading and staging

Grading

Grading refers to the appearance of the cancer cells under the microscope and gives an idea of how quickly the cancer may develop. Low grade means that the cancer cells look very like the normal cells and they are usually slowly growing and are less likely to spread. In high-grade tumours the cells look very abnormal and are likely to grow more quickly and are more likely to spread.

Ewing’s sarcomas are graded from 1 to 3. Grade 1 is a low-grade cancer and grades 2 and 3 are classed as high-grade cancer. Most Ewing’s sarcomas are high-grade cancers.

Staging

The stage of a cancer is a term used to describe its size and whether it has spread beyond its original site. Knowing the particular type and the stage of the cancer helps the doctors to decide on the most appropriate treatment.

Most patients are grouped depending on whether cancer is found in only one part of the body, which is known as localised disease, or whether the cancer has spread to another part of the body (metastatic disease).

• Stage 1A The cancer is low grade and is contained within the hard coating of the bone.
• Stage 1B A low-grade cancer which extends outside the bone into the soft tissue spaces, which contain nerves and blood vessels.
• Stage 2A The cancer is high grade and is contained within the hard coating of the bone.
• Stage 2B A high-grade cancer extending outside the bone into the soft tissue spaces, which contain nerves and blood vessels.
• Stage 3 The cancer can be low grade or high grade and is either within the bone or outside the bone. It has spread to other parts of the body, or to other bones not directly connected to the bone where the tumour started.

If the cancer comes back after initial treatment, this is known as recurrent cancer.

Treatments

Ewing’s sarcoma is treated by a combination of treatments which may include chemotherapy, surgery and radiotherapy. Treatment will depend on individual factors such as the position and the size of the tumour.

As Ewing’s sarcomas are very uncommon they are usually treated at specialist hospitals by a team of doctors and other health professionals. This means that you may have to travel some distance to have your treatment.

Most people with Ewing’s sarcoma will receive chemotherapy to shrink the primary tumour and also treat any cancer cells that may have spread to other parts of the body. Between 3 and 6 months later, the tumour will be treated with either surgery to remove the tumour, or radiotherapy. Chemotherapy will often continue after either surgery or radiotherapy.

Surgery

Major improvements in surgery for bone cancer have taken place. In the past, it was often necessary to remove the affected limb if Ewing’s sarcoma was found. Now, however, it is often possible just to remove the affected part of the bone and some of the healthy tissue around it. The bone is then replaced with a specially designed metal replacement (prosthesis) or a bone graft (bone taken from another part of the body). If the cancer affects a bone in or near a joint, the whole joint can often be replaced with an artificial one. These operations are known as limb-sparing surgery.

Unfortunately, it is not always possible to use limb-sparing surgery and occasionally an amputation may be the only way to treat the cancer. This is often the case when the cancer has spread from the bone into the nerves and blood vessels around it.

The type of surgery you have will depend on a number of factors. Your surgeon will discuss the different types of surgery with you in detail before any decision is made about your treatment.

It is often helpful to talk to someone who has had the same operation that you are going to have. The medical and nursing staff will be able to arrange this for you. On some wards a special counsellor may be available to discuss any worries you may have.

Chemotherapy

Chemotherapy is the use of anti-cancer (cytotoxic) drugs to destroy cancer cells. This is an important treatment for most people with Ewing’s sarcoma, as it can greatly improve the results of surgical treatment. It is often given before surgery and may shrink large tumours enough to avoid amputation.

The course of chemotherapy will then continue after surgery to destroy any remaining cancer cells and stop the sarcoma from spreading outside the bone. This is known as adjuvant chemotherapy.

Chemotherapy can make you feel better by relieving the symptoms of the cancer, but it can sometimes have unpleasant side effects. Any side effects that do occur can often be well controlled with medicine.

Radiotherapy

Radiotherapy treats cancer by using high-energy rays, which destroy the cancer cells, while doing as little harm as possible to normal cells.

Radiotherapy is often very effective in treating Ewing’s sarcoma and this treatment is often used after chemotherapy and before or after surgery. In some cases, surgery is not possible, for example if the tumour is in the spine. In these cases, radiotherapy may be given in place of surgery.

Radiotherapy can cause general side effects, such as feeling sick (nausea) and tiredness. These side effects can be mild or more troublesome, depending on the strength of the radiotherapy dose and the length of your treatment. The radiotherapist will be able to advise you what to expect.