Types Of Bone Cancer - Fibrosarcoma

Fibrosarcomas develop from fibrous (connective) tissue cells called fibrocytes. Fibrosarcoma occurs most commonly in adults, particularly during middle age. The most common site is the thigh bone (femur) and the knee.

As well as being a type of primary bone cancer, fibrosarcomas can develop in the soft tissues of the body. Soft tissue fibrosarcomas are very uncommon and include sclerosing epithelioid fibrosarcomas (SEF), desmoid tumours and dermato-fibrosarcoma protuberans (DFSP).

Malignant fibrous histiocytoma (MFH)

This is a very rare type of bone cancer that occurs in adults. It is usually found in the arms or legs, especially around the knee joint. These cancers start in fibrous tissue cells called histiocytes. This type of sarcoma tends to occur in older people (aged 40–80 years).

Malignant fibrous histiocytomas (MFH) can also develop in the soft tissues of the body, such as muscle. These tumours include storiform­pleomorphic, myxoid, giant cell, inflammatory and angiomatoid MFH.

Causes of fibrosarcoma and MFH

The exact causes of primary bone cancer are unknown. However, adults who have a bone condition known as Paget’s disease or who have been exposed to high doses of radiotherapy may have a slightly increased risk of developing bone cancer. Rarely, some bone cancers may occur in people from families where there is an inherited faulty gene that increases the risk of developing particular types of cancer.

Signs and symptoms

Pain is the most common symptom of bone cancer. However, symptoms may vary depending on the location and size of the cancer. There may be some swelling in the affected area and it may become tender to touch.

Occasionally a fever (high temperature) also develops. Primary 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, particularly 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 further investigations and decided if you need a referral to a specialist hospital or bone tumour centre for tests. Many of the specific tests for diagnosing bone tumours, such as the biopsy, require experience and specialist techniques.

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 energy beams 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.  

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’.

Needle biopsy

For this test a small sample of the tumour is taken from the affected bone. The doctor will look 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.

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 that shows detailed pictures of the inside of the body. A CT scan can show whether the cancer has spread to other parts of the body. The scan is painless and takes 10–30 minutes.  

Chest x-ray

In some people with fibrosarcoma or MFH the cancer may spread to the lungs. A chest x-ray is usually done to check whether there is any sign of cancer cells in the lungs.

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. 

Fibrosarcomas are graded from 1 to 4. Grades 1 and 2 are a low-grade cancer and grades 3 and 4 are high-grade cancer.

MFH are graded from 1 to 3. Grade 1 indicates a low-grade cancer and grades 2 and 3 are high-grade cancer.

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 from one part of the body to another (metastatic disease).

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

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

Treatments

The type of treatment you are given will depend on a number of things, including the position within the body of the cancer and its size, whether it has spread, the grade of the cancer and your general health.

As fibrosarcomas and MFH 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 either a fibrosarcoma or a malignant fibrous histiocytoma will need a combination of different treatments. The treatments that may be used are surgery (where this is possible), chemotherapy and radiotherapy.

Surgery is a very important part of treatment and is used to remove the tumour from the bone. If surgery is not possible, then radiotherapy may be used instead. Chemotherapy is not commonly used as a treatment for fibrosarcoma, however it may be helpful in some situations. In MFH it may sometimes be used to shrink the tumour before surgery.

Surgery

Major improvements have been made in surgery for bone cancer. In the past, it was often necessary to remove the limb if bone cancer 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 sometimes removing the whole affected limb (amputation) may be the only way to treat the cancer. This is often the case if 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 as 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 type of treatment is not commonly used to treat fibrosarcoma, although in certain situations it may be helpful.

People with a malignant fibrous histiocytoma may be offered chemotherapy to reduce to size of the tumour before surgery.

Chemotherapy can make you feel better by relieving the symptom 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. With fibrosarcoma, radiotherapy may be given to destroy any remaining cancer cells after surgery and can help to control the disease.

Radiotherapy is not often used to treat MFH, although it is still helpful in certain situations.

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.