Sarcomas are rare types of cancer that develop in the supporting structures of the body, such as bone, muscle or cartilage. There are two main types of sarcoma: soft tissue sarcomas and bone sarcomas.
Soft-tissue sarcomas can develop in muscle, fat, blood vessels or in any of the other tissues that support, surround and protect the organs of the body. Bone sarcomas can develop in any of the bones of the skeleton but may also develop in the soft tissue near bones.
Soft tissue sarcomas
Soft tissue sarcomas are rare tumours. Their annual incidence is around 2-3/100,000, and they account for less than 1% of all malignant tumours. In paediatric age, however, about 8% of all tumours are soft tissue sarcomas.
Half of the paediatric soft tissue sarcomas are rhabdomyosarcomas, half constitute the heterogeneous group of the so called "non-rhabdomyosarcoma" soft tissue sarcomas.
Rhabdomyosarcoma is the most common of the soft tissue sarcomas with approximately 5-6 children per million diagnosed each year. Most of them are younger than 10 years old. It is more common in boys than girls.
These tumours develop from muscle or fibrous tissue and can grow in any part of the body. The most common areas of the body to be affected are around the head and neck, the bladder or the testes. Sometimes tumours are also to be found in a muscle or a limb, in the chest or in the abdominal wall. Occasionally, if the tumour is in the head or neck region, it can spread into the brain or the fluid around the spinal cord.
Causes of rhabdomyosarcoma
The cause of rhadomyosarcoma is unknown. Research is going on all the time into possible causes of this disease. Children with certain rare genetic disorders, such as Li Fraumeni syndrome, have a higher risk of developing rhabdomyosarcoma.
Signs and symptoms
The signs and symptoms will depend on the part of the body that is affected by the rhabdomyosarcoma. The most common sign is a swelling or lump. If the tumour is in the head area it can sometimes cause blockage (obstruction) and a discharge from the nose or throat. Occasionally an eye may appear swollen and protruding. If the tumour is in the abdomen (tummy) the child may have discomfort in the abdomen and problems going to the toilet. If the tumour is in the bladder, the child may have blood in the urine and have difficulty passing urine.
How it is diagnosed?
A variety of tests and investigations may be needed to diagnose a rhabdomyosarcoma. These usually include a biopsy. This involves a small operation to remove a sample from the tumour to be looked at under a microscope. A biopsy is usually done under a general anaesthetic. Various tests may be done to check the exact size of the tumour and whether it has spread to any other part of the body. These may include:
The 'stage' of a cancer is a term used to describe its size and whether it has spread beyond the part of the body from which it originated. 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 the cancer is found in only one part of the body (localised disease) or whether the cancer has spread from one part of the body to another for example the lungs or bones (metastatic disease). The place in the body where the rhabdomyosarcoma started is also important information that is taken into account in the staging system.
Treatment depends upon some patient and tumour characteristics such as the size of the tumour, the subtype (when examined under the microscope) its position within the body, the age of the child or young person and whether it has spread. The treatment of rhabdomyosarcoma usually includes surgery, radiotherapy or chemotherapy, or a combination of these.
If possible, surgery will be used to remove the tumour, however if it cannot be easily removed then it is often better to shrink it down with chemotherapy before attempting further surgery.
Chemotherapy using a combination of drugs is often given before surgery to shrink the tumour. Chemotherapy is the use of anticancer (cytotoxic) drugs to destroy cancer cells. Your doctor will give you more details about the chemotherapy that will be used.
Radiotherapy may be given to the area of the tumour. If the tumour cannot be removed with surgery the treatment will usually involve a combination of chemotherapy and radiotherapy.
Radiotherapy treats cancer by using high-energy rays that destroy the cancer cells, while doing as little harm as possible to normal cells.
Side effects of treatment
Treatment for rhabdomyosarcoma often causes side effects, and your child's doctor will discuss these with you in some detail before treatment starts. Any possible side effects will depend upon the particular treatment being used and, when radiotherapy is being given, the part of the body that is being treated. Side effects can include: nausea (feeling sick) and vomiting, hair loss, an increased risk of infection or bruising and bleeding, tiredness constipation and diarrhoea.
Late side effects
A small number of children may develop side effects many years after their treatment for a rhabdomyosarcoma. Longer-term side effects depend on the type of treatment used, and may include possible reduced growth, infertility, a change in the way the heart and the kidneys work, hearing problems and a small increase in the risk of developing another cancer in later life. If your child has received daunorubicin (and anthracycline chemotherapy) then your child may have a small risk of developing heart problems. He/she will have been monitored throughout treatment and following completion of this therapy.
Overall about two thirds of all children with rhabdomyosarcoma are cured, but the particular risks for your child will be discussed by your doctor. After treatment the doctors will regularly check the child to be sure the cancer has not come back and to look for any long term side effects of the treatment. After a while you will not need to visit the clinic so often. If you have specific concerns about your child's condition and treatment, it is best to discuss them with your child's doctor, who knows the situation in detail.
NON-RHABDOMYOSARCOMAS SOFT TISSUE SARCOMAS
This definition includes different tumours with different biology and natural history, some of which are more common in adults. These tumours can arise, generally as a soft part enlarging mass, anywhere in the body (most frequently in the muscles of extremities, less usually in the trunk or head and neck region). The cause of their origin is unknown, and researchers are studying possible causes: it is known that children with certain rare genetic disorders, such as Li Fraumeni syndrome or neurofibromatosis, have a higher risk of developing soft tissue sarcomas. However, the majority of soft tissue sarcomas are sporadic.
Usually, non-rhabdomyosarcoma soft tissue sarcomas are characterized by local aggressiveness. Metastases are rare at the time of diagnosis; when they occur, they are frequently localized at the lung. The propensity to metastasize is directly correlated to the grade of malignancy. Generally, low-grade tumours usually may have local aggressiveness but low tendency to metastatic spread. High-grade tumours have a more invasive behaviour with higher propensity to metastasize. Overall, the majority of patients with soft tissue sarcomas can be cured, even if the probability of cure depends on the degree of malignancy and the stage of the disease.
The most common sign that leads to the diagnosis of soft tissue sarcomas is a growing swelling or lump. Other signs and symptoms depend on the part of the body where the tumour arises.
Various exams are necessary for the full diagnosis of soft tissue sarcomas. First of all, biopsy is needed for defining the histological diagnosis: a small sample of the tumour is taken and looked under a microscope, so that the pathologist can give the exact name of the tumour.
Then some tests are necessary to define the stage of the tumour (size, local invasiveness, spread in other part of the body): CT or MRI scan of the part of origin of the tumour, chest x-ray and CT-scan, abdominal ultrasound, bone scan are generally performed.
Knowing the particular type and the stage of the tumour is very important for deciding the most appropriate treatment.
The treatment of patients with soft tissue sarcomas is complex and may necessitate multidisciplinary approach, including surgery, radiotherapy and chemotherapy. The treatment depends upon the type of the tumour and its grade of malignancy, the size of the tumour, and the possibility to remove it with a safety surgery.
Surgery is the mainstay of treatment. If possible, surgery will be used to completely remove the tumour. If the tumour cannot be completely removed without mutilation or functional sequelae, radiotherapy and chemotherapy should be used to shrink the tumour down and facilitate a subsequent operation.
Radiotherapy may be given to the area of origin of the tumour: high-energy rays can destroy tumour cells, but it is important to know that irradiation might cause late side effects (i.e. possible reduced growth of the irradiated part) that are difficult to foresee, but must be taken into account when the treatment strategy is discussed.
Chemotherapy is a combination of drugs that can destroy tumour cell with a cytotoxic mechanism. It is usually administered every three weeks: given intravenously, it can act against every tumour cell presents in the body, also against those spreading away from the site of origin of the tumour. Chemotherapy can be associated to nausea and vomiting, hair loss and increased risk of infection. With the exception of some particular histotypes, non-rhabdomyosarcoma soft tissue sarcomas are generally considered tumours with uncertain chemosensitiveness. But recent data would seem to suggest that chemotherapy may play a more significant role than is generally believed in some subsets of patients for which the risk of failure is high. Your doctors will explain you possible benefits and disvantages of the treatment choices.