Neuroblastoma

17 January 2012

Neuroblastoma is the second most common solid tumour in childhood, affecting just under 100 children a year in Britain.

Neuroblastoma is the most common type of embryonal tumour. It is a cancer of specialised nerve cells, called neural crest cells. These cells are involved in the development of the nervous system and other tissues.

Neuroblastoma can occur anywhere in the body, but it most often occurs in one of the adrenal glands, in the abdomen.

In some children, the neuroblastoma occurs in nerve tissue alongside the spinal cord in the neck, chest, abdomen or pelvis.

Incidence

Neuroblastoma accounts for six per cent of childhood cancer registrations in Britain – just under 100 children a year.

As with all embryonal tumours, neuroblastoma is most common in children under the age of 5 years, and extremely rare after the age of 10 years.

The incidence of neuroblastoma is highest in the under ones – it is the most frequent single type of cancer in the first year of life, accounting for one fifth of cancers in this age group.

Neuroblastoma is slightly more common in boys, by a ratio of 6:5.

Causes

The causes of neuroblastoma are not known.

Survival

Neuroblastoma has one of the lowest survival rates of all childhood cancers at 64 per cent.

It is also one of the few types of cancer for which survival differs significantly between the sexes – boys have a worse outlook than girls.

Infants have a better outlook than older children: those diagnosed before the age of one year have five-year survival of 83 per cent compared to only 43 per cent for those in the 1 to 4 year age group.

Diagnosis

The first symptoms of neuroblastoma are generally vague, such as loss of appetite, tiredness and pain in the bones.

Other symptoms vary, depending on where the child’s neuroblastoma starts.

If it is in their abdomen, their tummy may be swollen and they may complain of constipation or difficulty passing urine.
If the tumour is in the chest or neck area, the child may be breathless and have difficulty swallowing.
Occasionally there may be deposits of neuroblastoma in the skin that appear as small, blue-coloured lumps.
If the tumour is pressing on the spinal cord, it may cause weakness in the legs.

A variety of tests and investigations may be needed to diagnose a neuroblastoma. These include blood, urine or bone marrow tests, x-rays, CT or MRI scans and mIBG scans (see below). These tests confirm the diagnosis and help doctors to determine the best way to treat the tumour.

Nearly all children with neuroblastoma will have substances called vanillylmandelic acid (VMA) or homovanillic acid (HVA) in the urine. These substances, known as tumour markers, are produced by the tumour cells and measurement not only helps to confirm the diagnosis but also helps to monitor the effectiveness of treatment since levels will fall if the treatment is working.

mIBG is a substance that is taken up by neuroblastoma cells. It is given by injection. Attaching a small amount of radioactive iodine to the mIBG enables the tumours to be seen by a radiation scanner. mIBG may also be used as a treatment.

Other tests look at the chromosomes and ‘biological markers’ in tumour cells taken by biopsy to help determine the type and intensity of treatment. If a certain level of a marker called MYCN is detected it indicates that the tumour is high-risk and that treatment needs to be more intensive.

Treatment

For early-stage tumours which have not spread, surgery alone may be sufficient to get rid of the cancer. If the tumour is classed as high risk, chemotherapy and possibly radiotherapy will also be needed. If the tumour is too large or in too difficult a position to remove safely, chemotherapy will be given to shrink it before surgery.

If the neuroblastoma has spread to several parts of the body or is high-risk with MYCN amplification, high-dose chemotherapy is used to eradicate any remaining neuroblastoma cells. High-dose chemotherapy also destroys the child’s bone marrow, however, and stem cell rescue will be required. where blood cells are made. This involves collecting blood stem cells from the child before chemotherapy and returning them afterwards, via a drip. The stem cells make their way back into the bone marrow where they grow and develop into mature blood cells over a period of several weeks.

Radiotherapy may be used if the neuroblastoma is classed as high-risk or if it has spread to several parts of the body. This may be either external radiotherapy, delivered from a machine outside the body, or internal radiotherapy using radioactive mIBG.

Children under 18 months old generally have a good outlook. Most neuroblastomas in this age group regress spontaneously, without treatment. Treatment will only be given if the tumour is causing life-threatening symptoms or if it has spread to the bone, lungs or central nervous system.

A new monoclonal antibody treatment called anti-GD2 is currently being tested for people with high-risk neuroblastoma. Monoclonal antibodies can destroy some types of cancer cells while causing little harm to normal cells. Reports suggest that this may be a promising therapy when given alongside other standard treatment for neuroblastoma; however it has unpleasant side-effects and is still undergoing trial. It is currently only available to children in the UK who are being treated within a clinical trial.

Side effects of treatment

Treatment often causes side effects and these will be discussed with you before treatment starts.

The possible side effects depend on the treatment given and the part of the body being treated but may include nausea and vomiting, hair loss, reduced resistance to infection, bruising and bleeding, tiredness and diarrhoea.

These problems are all temporary and can be minimised with good supportive care.

Read more: Side effects of treatment

Long-term follow up

Children will have regular follow-ups to check for any recurrence of the cancer and for any problems which may arise as a result of the treatment they were given.

A small number of children may develop long-term problems because of the treatment they received for neuroblastoma.

These include possible problems with heart and kidney function, hearing problems, fertility problems, a possible reduction in bone growth if radiotherapy has been used, and a small increase in risk of developing another cancer.

Read more: Long-term and late effects of treatment

References:
Cancer in Children: Clinical Management (5th edition). Eds: P A Voute, Ann Barrett, Michael C G Stevens and Hubert N Caron. Oxford University Press, 2005.
Childhood Cancer in Britain: incidence, survival, mortality. Ed by Charles Stiller. Oxford University Press, 2007.
Macmillan Cancer Support factsheet - Neuroblastoma in children (2010).

Related Topics types of childhood cancer, Neuroblastoma

Categories types of childhood cancer