Childhood Cancer incidence statistics
Many types of cancer that occur in children are hardly ever seen in adults; conversely, the cancers most frequently seen in adults in developed countries – carcinomas of the lung, female breast, prostate and large bowel – are all extremely rare among children. For adults, cancer incidence data can be classified largely in terms of the site of the disease; for children the cell type (histology) also needs to be taken into account.
Around 1,500 new cases of childhood cancer are diagnosed each year in the UK, about 20% more in boys than in girls (Table 1.1)1-2.
This page includes incidence data for the most commonly diagnosed cancers in British children:
- Leukaemias
- Lymphomas
- Brain and spinal tumours
- Embryonal tumours
- Bone tumours
- Soft tissue sarcomas
- Germ cell and gonadal tumours
- Carcinoma and melanoma
The risk for an individual child in Britain of being diagnosed with cancer before the age of 15 is about 1 in 500. This is made up of risks of about 1 in 1600 for leukaemia, 1 in 2200 for a brain or spinal tumour and 1 in 1100 for all other cancers combined.
Different types of childhood cancer have widely varying distributions of age at diagnosis, illustrated by age-specific incidence curves in Figure 1.1 and shown below1.
Leukaemias
The proportions of the leukaemia subtypes seen in children are completely different from those seen in adults.
By far the most common type in childhood is acute lymphoblastic leukaemia (ALL). In Britain this makes up about four-fifths of childhood leukaemias and thus a quarter of all childhood cancers.
The age-specific incidence curve for ALL in Britain has a clear peak between the ages of one and six, with the highest rates at ages two and three. This is typical for an affluent Western population; the peak is less marked in less developed countries.
ALL is about 30% more frequent in boys than in girls. Acute nonlymphocytic leukaemia, consisting in children almost entirely of acute myeloid leukaemia (AML), is only about 15% of childhood leukaemias, and chronic myeloid leukaemia is less than 4%. AML is about 20% more frequent in boys than in girls.
Lymphomas
Lymphomas are more than twice as common in boys as in girls, and very rarely occur before the age of about two.
There are two main types of lymphoma: Hodgkin’s disease and non-Hodgkin lymphomas (NHL). The incidence of Hodgkin’s disease increases steadily with age. The incidence of NHL hardly changes between the ages of three and fourteen.
Brain and spinal tumours
About three quarters of this large and varied group can be classified as either astrocytoma (two fifths of the group), primitive neuroectodermal tumour (PNET) (a fifth) or ependymoma (a tenth).
The most common type of PNET is medulloblastoma, which belongs to the group of embryonal tumours (see below). Astrocytoma is equally frequent in boys and girls, whereas PNET is 60% more common in boys than in girls.
Embryonal tumours
This broad group of childhood tumours crosses over the standard classification, because embryonal tumours occur in many different parts of the body. They include medulloblastoma in the brain, neuroblastoma in the sympathetic nervous system, retinoblastoma in the eye, Wilms’ tumour (nephroblastoma) in the kidney, hepatoblastoma in the liver and embryonal rhabdomyosarcoma in soft tissue.
They are characterised by the proliferation of tissue that is normally seen only in the developing embryo. They are generally very rare after childhood, and occur most commonly in the first few years of life. Several types of embryonal tumour have a peak of incidence in the first year of life. Some types are occasionally found to be present at birth.
Bone tumours
The two main types of bone tumour that occur in childhood – osteosarcoma and Ewing’s sarcoma of bone – are very rare in children under five years, increase in incidence with age and peak in adolescence, probably because this is the peak time of bone growth.
Unlike most childhood cancers, osteosarcoma, the larger category of bone tumours, is slightly more common in girls than in boys between the ages of seven and thirteen, perhaps reflecting the earlier age of puberty in girls.
Soft tissue sarcomas
More than half of soft tissue sarcomas in childhood are classified as rhabdomyosarcomas, which derive from primitive striated muscle cells. Most childhood rhabdomyosarcomas are of the embryonal type, with the highest incidence in the first few years of life.
Among the “other specified” category (see Appendix), about half the tumours are of the Ewing’s sarcoma family and the remainder are a wide variety of rarer types.
Germ cell and gonadal tumours
Although male and female gonadal germ cell tumours are grouped together in the standard classification, their constituent subtypes are different and they have entirely different age distributions.
The incidence in boys peaks very early at around 2-3 years old while the incidence in girls is low until age 6 or 7 when it begins to increase up to age 15.
Carcinoma and melanoma
Most of these cancers are very rare in early childhood, increase in incidence steadily with age, and are much more common in adults.
Unusually for childhood cancers, melanoma and several types of carcinoma are more common in girls than in boys.
Geographical variation in incidence
There was little variation in age-standardised rates between the English Government Office Regions,Wales and Scotland in the period 1971-971.
There seems to have been some variation in incidence rates between large cancer registries in various European countries within the period 1993-97 (Figure 1.23), although this may be partly explained by chance.
In Eastern Europe, the incidence of ALL was somewhat lower than in the west and the peak in early childhood was less marked. Recent results from the Czech Republic indicate that the incidence of ALL among children aged 1-4 years in Eastern Europe has been increasing with improved socio-economic conditions, resulting in a more marked early childhood peak4.
The high rate for cancers other than leukaemias and brain and spinal tumours in Belarus is accounted for by a sharp increase in thyroid cancer following the explosion at Chernobyl in 1986.
References
- UK Childhood Cancer Research Group, National Registry of Childhood Tumours. 2004.
- Northern Ireland Cancer Registry, Cancer Incidence and Mortality
- IARC, Automated Childhood Cancer Information System (ACCIS),
- Hrusak, O., et al., Acute lymphoblastic leukemia incidence during socioeconomic transition: selective increase in children from 1 to 4 years. Leukemia, 2002. 16(4): p. 720-5
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