Rhabdomyosarcoma

What is rhabdomyosarcoma?

A rhabdomyosarcoma is a type of soft tissue sarcoma. A sarcoma is a tumour that starts in the supporting tissues (connective tissues) of the body - for example, bone, muscle, fat, cartilage and ligaments.

Rhabdomyosarcomas grow in the muscles of the body. Rhabdomyosarcoma can occur anywhere in the body. There are three types of rhabdomyosarcoma which affect different age groups:

See separate leaflet called Cancer - A General Overview for more general information about cancer

Embryonal rhabdomyosarcoma

This most often affects young children, usually under the age of 6 years. It most often occurs in the head and neck region, especially in the tissues around the eye (called an orbital rhabdomyosarcoma). Embryonal rhabdomyosarcoma may also occur in the womb, vagina, bladder or the prostate gland. One type of embryonal rhabdomyosarcoma is called sarcoma botryoides, which looks like a bunch of grapes and most often occurs in the vagina or bladder.

Embryonal rhabdomyosarcomas usually spread to surrounding tissues. However, the outcome (prognosis) is usually very good and most children with embryonal rhabdomyosarcoma are cured of the cancer.

Alveolar rhabdomyosarcoma

This tends to occur in older children and young adults. Alveolar rhabdomyosarcomas most often occur in the arms and legs, chest or tummy (abdomen).

Pleomorphic rhabdomyosarcoma

This tends to occur in middle-aged adults. It is usually treated with chemotherapy, surgery and radiotherapy but treatment is not as effective as for other types of rhabdomyosarcoma.

Rhabdomyosarcomas are rare. Rhabdomyosarcomas can occur at any age but are much more common in children and only rarely affect adults. Fewer than 60 children are diagnosed each year in the UK. Most of these children are aged under 10 years.

The exact causes of rhabdomyosarcomas are unknown. Rhabdomyosarcomas are slightly more common in children with certain genetic disorders such as neurofibromatosis or Li-Fraumeni syndrome.

Soft tissue sarcomas may occur in an area that has previously been treated with radiotherapy for another type of cancer. The sarcoma usually doesn't develop until at least 10 years after the radiotherapy treatment.

Studies have also reported an increased risk with high birth weight, exposure to X-rays while in the mother's womb before birth, childhood infections and childhood exposure to certain chemicals.

Rhabdomyosarcomas may cause a variety of symptoms, depending on which part of the body is affected. Symptoms may include:

• A lump (tumour), which may be painful.

• The tumour may bleed and cause bleeding from the nose, vagina, throat or back passage.

• The tumour may press on nerves and cause tingling, numbness, pain and weakness in that area of the body.

• A rhabdomyosarcoma in the nose may cause obstruction of the air passage, and discharge.

• An orbital rhabdomyosarcoma may cause the eye to be pushed forward (protrude), or cause the eyelid to droop.

Any child or adult who has any symptoms suggesting the possibility of a cancer such as rhabdomyosarcoma should be seen urgently (within a maximum of two weeks) by a specialist.

The tests to make a diagnosis and see whether the rhabdomyosarcoma has spread to other parts of the body will include: blood tests, chest X-ray, ultrasound scan of the tummy (abdomen), CT scan, MRI scan, bone scan and a PET scan.

A biopsy is the only way to confirm the diagnosis. A small piece of tissue is removed from the tumour and the cells are looked at under a microscope. Further tests can then find out exactly what type of sarcoma it is.

Grading is very important to decide on the best treatment and to know how likely it is that the cancer can be cured.

• Low-grade. The cancer cells are similar to normal cells. Low-grade cancers usually grow slowly and are less likely to spread to other parts of the body.

• High-grade. The cells are very abnormal. High-grade cancers grow more quickly and are likely to spread to other parts of the body. Embryonal and alveolar types of rhabdomyosarcoma are always high-grade.

Localised disease means that the cancer has not spread to other parts of the body. Metastatic disease means that the cancer has spread to other parts of the body. There are different systems used for staging but sarcomas can be divided into four stages:

• Stage 1. The sarcoma is localised.

• Stages 2 or 3. The sarcoma has spread to the surrounding tissues but not to any distant site in the body.

• Stage 4. The sarcoma has spread into other parts of the body.

Other factors that are now used for staging include the site of the tumour (better outcome for some sites - for example, head and neck, vagina or womb) and the size of the tumour.

The treatment depends on the type of rhabdomyosarcoma and the stage of the cancer. Regular appointments with a specialist are needed after treatment, in order to check whether the cancer has come back.

The treatments include surgery, chemotherapy or radiotherapy, or a combination of all three. Surgery may be used on its own for small localised tumours.

Chemotherapy and radiotherapy may be used:

• To reduce the size of the tumour before surgery.

• To reduce the risk of the cancer coming back after surgery.

• For people who are not able to have surgery.

The complications of neuroblastoma depend on which parts of the body are affected. Although modern treatments are very effective and life-saving, the treatments may also cause long-term complications.

The risk of complications caused by treatments is very small compared with the benefits of treatments, which are often life-saving and successfully cure the neuroblastoma. The complications of treatments are becoming less common as treatments improve but may include:

• Fertility problems.

• Hearing problems.

• Growth problems.

• Kidney and heart problems.

• An increased risk of developing another cancer.

About 2 in every 3 children with rhabdomyosarcoma will be cured with treatment. The embryonal type is the most treatable and has the highest rate of cure.

The outcome will also depend on which part of the body is affected. Rhabdomyosarcomas affecting the eye or the womb, vagina, bladder or prostate gland (genitourinary tract) have the best chance of effective treatment and cure.