Overview
Childhood cancers are rare and are quite different from the cancers that affect adults in their behaviour and treatment. Whilst it is devastating for any parent to learn that their child has cancer, the prognosis for most children with cancer is better than for most adults.
Leukaemia and brain tumours are the most common childhood cancers - making up 75% of the total. Most health professionals are unlikely to come across any of the other childhood cancer types during their careers.
Cure rates for childhood cancers are high with over 70% of all children being completely cured. Furthermore, these figures are improving all the time as refinements are made to current therapies and new treatments are introduced.
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Key Figures
There is no European cancer registry data on childhood cancers.
In the USA, the Surveillance, Epidemiology and End Results (SEER) Program of the National Cancer Institute (NCI) provides age-adjusted incidence rates for childhood cancers for the years 1975 – 1995. These figures are over 10 years out of date but have probably not changed to any significant degree. Although these figures are North American data, the European incidence rate is thought to be broadly similar.
Quoted incidences are given in numbers of children per million per year:
| Leukaemia |
37 |
| Lymphoma |
24 |
| Brain/CNS |
25 |
| Neuroblastomas |
7 |
| Retinoblastomas |
3 |
| Wilms' tumour |
6 |
| Hepatic (liver) cancers |
2 |
| Rhabdomyosarcoma and other soft tissue tumours |
11 |
| Germ cell tumours |
14 |
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Cancer Types
Childhood Leukaemia
A form of malignancy affecting the white blood cells. Acute Lymphoblastic Leukaemia (ALL) is the most common form of leukaemia in children.
A proliferation of abnormal white cells reduces production of normal cells in the bone marrow and results in a range of non-specific symptoms including:
- generalised weakness and fatigue
- infections
- bruising and bleeding
- bone and joint pain
- an enlarged spleen and lymph nodes.
The onset of these symptoms is rapid.
Medulloblastoma
The most common form of brain tumour in children. It causes headaches, nausea and vomiting due to raised intracranial pressure. Medulloblastomas grow in the cerebellum and tend to spread within the central nervous system. The majority of children with medulloblastoma are cured, with long term survival rates of 70-80%.
Neuroblastoma
Usually affects children under five years old. It starts most often in the nerve tissue of the adrenal glands but it can also develop from nerve tissue near the spine, in the abdomen, chest and neck or in the spinal cord.
Neuroblastomas grow and spread quickly affecting nearby lymph nodes, bones, bone marrow, liver and skin.
Lymphomas
These are tumours that develop from cells of the lymphatic system. There are two main groups of lymphomas - Hodgkin's and Non-Hodgkin's lymphomas. Up to three children per 100,000 will develop lymphoma in childhood - making up about 10% of childhood cancers.
Wilms' tumour
A rare childhood form of kidney (renal) cancer which makes up about 6% of all childhood cancers. The average age at diagnosis is three and a half. Treatment with surgery, chemotherapy and (sometimes) radiotherapy is very successful in curing 80-90% of Wilms' tumours in children.
Rhabdomyosarcomas
Tumours arising from primitive muscle cells, that would normally develop into striated muscle cells. They account for 5-8% of childhood cancer, usually affecting children aged 2 to 6 and teenagers aged 15 to 19 years old. The most common sites for rhabdomyosarcomas are:
- the head and neck and around the eyes
- the arms and legs
- the chest
- the genito-urinary tract
Retinoblastomas
Develop from cells in the retina in the eye and contain very primitive cells. These tumours usually affect children under five and can affect one or both eyes. 40% of retinoblastomas are hereditary.
The treatment for retinoblastomas depends on how early the diagnosis is made - wherever possible the eye is preserved.
Germ cell tumours
Rare tumours developing in the foetus from cells that should become the ovaries and testes. Most of these tumours are benign and are very rare in children younger than 15 years. In most germ cell tumours there is no obvious cause, however, there is a higher risk of testicular germ cell tumours in males with undescended testes.
Osteosarcomas
Osteosarcomas are malignant tumours arising from the bones. Usually they develop at the growing point (metaphysis) of the long bones in the arms and legs and, most commonly, in the knee. They can also occur in the shoulder, pelvis and skull. They typically affect teenagers and are twice as common in males.
Ewing's sarcoma
Ewing's sarcoma accounts for 10-15% of childhood bone cancers and 1% of all childhood cancers. It is most common in 10 to 20 year-olds. The tumour is made up of small, round, blue cells and usually occurs in the pelvis, thigh, lower leg, upper arm or ribs. The first symptom is usually a lump where the tumour is growing which may be noticed for the first time after a fall or some other injury. Often it is assumed that the tumour is a result of the injury. However, it is likely that the fall has only drawn attention to a lump that was already there.
Childhood liver tumours
These are very rare but they are more common in boys than girls. There are two main types of cancer developing from liver cells:
- Hepatoblastoma - usually occurs in children under five years of age
- HepatoCellular Carcinoma (HCC) - exceptionally rare and usually occurs in older children.
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Causes of Childhood Cancers
For the majority of childhood cancers there is no known cause but those with clear risk factors are listed below.
Acute Lymphoblastic Leukaemia – Down’s syndrome and Fanconi’s syndrome are known to be associated with a higher risk of developing leukaemia.
40% of retinoblastomas are hereditary.
There is a higher risk of testicular germ cell tumours in males with undescended testes.
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Prevention of Childhood Cancer
Even for those childhood cancers which have clear risk factors, there are no practical measures that can be taken to prevent the cancer from developing.
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Common Symptoms
Childhood cancers include a diverse range of conditions. The presenting symptoms are equally varied and depend on the site of the original tumour and the effects on nearby structures.
Leukaemias cause a range of non-specific symptoms including:
- generalised weakness and fatigue
- infections
- bruising and bleeding
- bone and joint pain
- an enlarged spleen and lymph nodes
The onset of these symptoms is rapid.
Brain tumours do not cause the same symptoms in every child but often include:
- headaches - which are worse in the morning
- nausea and vomiting
- problems with vision, hearing, and speech
- loss of balance - being clumsy and unsteady
- sleepiness
- personality or behavioural change
- seizures (convulsions), movement or sensation changes
- in infants - an increase in head size
The symptoms of spinal cord tumours are:
- pain in the back
- incontinence or difficulty in going to the toilet
- weakness in the legs - stumbling and falling over
- difficulty in walking
Lymphomas typically cause:
- painless swellings in the neck, chest, underarm, or groin (due to an enlargement of the lymph nodes)
- fever
- night sweats
- unexplained weight loss
- an itchy skin
Other tumours are first diagnosed after a lump is found.
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Diagnostic Tests
The combination of symptoms and clinical findings on examination will often be indicative of a particular form of tumour, however, as with all cancers a definitive diagnosis requires a biopsy.
Obtaining an exact diagnosis is imperative. Many forms of childhood cancer have subtypes and different grades, which will influence treatment.
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Treatment
Available treatments for childhood cancer include:
- surgery
- radiotherapy
- chemotherapy
- chemoradiation – combined radiotherapy and chemotherapy
Patients may receive some or all of these treatments.
Leukaemia
Chemotherapy (the use of drugs to destroy abnormal cells) is the main treatment for acute lymphoblastic leukaemia, with a combination of drugs given in a series of treatment blocks. Treatment is usually given in three phases:
- Induction - high dose chemotherapy to destroy the vast majority of leukaemia cells and produce a remission
- Consolidation - further chemotherapy to destroy the remaining leukaemia cells
- Maintenance - lower dose chemotherapy designed to prevent the re-emergence of the leukaemia.
In addition, radiotherapy is sometimes given to the brain if leukaemia cells are found in the fluid around the spine (or to prevent recurrence of the disease in the meninges in high risk patients). In very particular cases, radiotherapy is given to boys’ testicles as leukaemia cells can survive there even after chemotherapy.
Stem cell (bone marrow) transplants may be used in a small number of patients where it proves impossible to eradicate the disease using drug treatment alone. Before a transplant can take place, high-dose chemotherapy and/or radiotherapy is given to destroy the patient’s existing bone marrow. Transplants work best early in the course of the disease.
Brain and spinal cord tumours
Surgical removal of the tumour, as far as is reasonably possible, with radiotherapy and/or chemotherapy to destroy any cells that have not been removed during surgery (adjuvant treatment).
Brain surgery is usually the preferred treatment option for brain tumours, provided the tumour is accessible. If removing the tumour is not possible without damaging normal brain tissue, radiotherapy may be the better option. However, surgery may still be required later on in these cases to obtain a biopsy to confirm the diagnosis or to relieve symptoms caused by raised intracranial pressure.
The object of surgery is always the same - to remove as much of the tumour as possible without damaging normal brain tissue. Tumour tissue left behind is usually treated with radiotherapy, however, in young children (under 3 years old) chemotherapy may be preferred to avoid long term side effects.
Neuroblastomas
Treated with surgery to remove the tumour, followed by chemotherapy, and then very careful monitoring once the treatment has finished. Very rarely, radiotherapy is used after surgery to kill any cancer cells that have not been removed during surgery.
Lymphomas
Generally treated with radiotherapy, chemotherapy and, in some cases, a bone marrow transplant. Radiotherapy can be combined with chemotherapy in the treatment of lymphoma.
Chemotherapy is the primary form of treatment for NHL, and is generally important in treatment of Hodgkin's disease too. Children with Stage I Hodgkin's disease or NHL may be treated with radiation alone. However, with children who have a more advanced stage disease at the time of diagnosis, chemotherapy is used, sometimes together with radiation.
Wilms' tumour
Treated with surgery and chemotherapy, and sometimes radiotherapy. Treatment is very successful in 80-90% of children.
Rhabdomyosarcomas
Treated with a combination of surgery to remove the tumour and chemotherapy and/or radiotherapy to shrink the tumour before surgery or to reduce the risk of the cancer returning after surgery.
Retinoblastomas
Treated with surgery, chemotherapy, cryotherapy (a way of destroying cancer cells by freezing them), light coagulation or radiotherapy. It is not usually necessary to remove the eye.
Germ cell tumour
Treatment may include surgery to remove the tumour, chemotherapy, radiotherapy and less commonly, bone marrow transplantation. In the long term, hormone replacement may also be necessary. Some specific issues related to the conservation of fertility may be important according to the disease presentation.
Osteosarcoma
Treatment depends on the exact type of osteosarcoma. Therapy is usually a combination of surgery (removing the tumour and replacing the bone with a bone graft or metal rod) and chemotherapy (usually ifosfamide, cisplatin, methotrexate, and doxorubicin). Radiotherapy is rarely used in treating osteosarcomas.
Ewing’s sarcomas
Highly responsive to radiotherapy (unlike osteosarcomas) and so are often treated with radiotherapy after surgery and chemotherapy.
Childhood liver tumours
Usually treated with chemotherapy followed by surgery. In very select cases a specialised form of radiotherapy (stereotactic radiotherapy) can be used as an alternative to surgery. In some cases a liver transplant will be necessary.
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Prognosis
Acute lymphoblastic leukaemia (ALL)
Children: as many as 85% of children with ALL will be cured.
Brain and spinal cord tumours
There are many different forms of brain tumour which occur in childhood, so general figures on prognosis are not meaningful.
Medulloblastoma
Medulloblastoma is the most common brain tumour in children. Prognosis for this tumour has improved dramatically from 20% to 80% of children being disease free and potentially cured five years from diagnosis. This improvement in cure rates is due to combined modality treatment with surgery, radiotherapy and chemotherapy.
Neuroblastomas
Children of any age with a localised neuroblastoma and infants who are under 1 year and displaying an advanced disease have a high likelihood of long term, disease free survival. Older children with advanced-stage disease, however, have a significantly lower chance (approximately 30%) of a cure, even with intensive therapy.
Lymphomas
90% of children with Hodgkin's disease go into remission following initial chemotherapy. Almost all children with early stages of the cancer (Stage I or Stage II) are then disease-free for 5 years or longer. Up to 90% of Stage III patients, and over 60% of patients with Stage IV Hodgkin’s disease are disease-free for 5 years or longer.
90% of children with Non-Hodgkin’s Lymphoma who were at Stage I or Stage II at the time of diagnosis are disease free for five years or longer. 70% of children with more advanced Stage III or IV of the disease are disease-free for five years or longer.
Wilms' tumour
Treatment is very successful in 80-90% of children.
Rhabdomyosarcomas
In the 1970s, the outlook for children with rhabdomyosarcoma was poor with 5 year survival rates of less than 20%. With modern treatment, the cure rate has risen to approximately 70%.
Retinoblastomas
In the western world, nearly 98% of children survive. In less advanced countries, about 50% of children with retinoblastomas die from dissemination of the tumour.
Germ cell tumour
There are many different types of germ cell tumour. Prognosis depends on the extent of the disease, the size and location of the tumour and whether it has metastasised, response to therapy, and the child’s age.
Osteosarcoma
Localised osteosarcomas have a 5 year survival rate of over 55% and many of these children will be cured.
Ewing’s sarcomas
Of patients with Ewing's sarcoma that is localised and has not spread elsewhere in the body, over 60% live for at least 5 years after diagnosis and many of these children will be cured.
Childhood liver tumours
Childhood liver cancer may be cured if the tumour is small and can be completely removed by surgery. Complete removal is possible more often for hepatoblastoma than for hepatocellular carcinoma.
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Key Trends
- Genomic testing to assess susceptibility of children to childhood cancers and potential response to treatment.
Important Research Areas
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