Childhood cancer

A girl trying out hats to wear after chemotherapy against a Wilms' tumor, which is a cancer type that typically occurs in children.^[1]

Childhood cancer (also known as pediatric cancer) is cancer in a child. In the United States, an arbitrarily adopted standard of the ages used are 0–14 years inclusive, that is, up to 14 years 11.9 months of age.^[2][3] However, the definition of childhood cancer sometimes includes young adults between 15–19 years old.^[3] Pediatric oncology is the branch of medicine concerned with the diagnosis and treatment of cancer in children.

Worldwide, it is estimated that childhood cancer has an incidence of more than 175,000 per year, and a mortality rate of approximately 96,000 per year.^[4] In developed countries, childhood cancer has a mortality of approximately 20% of cases.^[5] In low resource settings, on the other hand, mortality is approximately 80%, or even 90% in the world's poorest countries.^[5] In many developed countries the incidence is slowly increasing, as rates of childhood cancer increased by 0.6% per year between 1975 and 2002 in the United States^[6] and by 1.1% per year between 1978 and 1997 in Europe.^[7]

Types

The most common cancers in children are (childhood) leukemia (34%), brain tumors (23%), and lymphomas (12%).^[7] In 2005, 4.1 of every 100,000 young people under 20 years of age in the U.S. were diagnosed with leukemia, and 0.8 per 100,000 died from it.^[8] The number of new cases was highest among the 1–4 age group, but the number of deaths was highest among the 10–14 age group.^[8]

In 2005, 2.9 of every 100,000 people 0–19 years of age were found to have cancer of the brain or central nervous system, and 0.7 per 100,000 died from it.^[8] These cancers were found most often in children between 1 and 4 years of age, but the most deaths occurred among those aged 5–9.^[8] The main subtypes of brain and central nervous system tumors in children are: astrocytoma, brain stem glioma, craniopharyngioma, desmoplastic infantile ganglioglioma, ependymoma, high-grade glioma, medulloblastoma and atypical teratoid rhabdoid tumor.^[9]

Other, less common childhood cancer types are:^[9]

• Neuroblastoma (7%, nervous system)
• Wilms tumor (5%, kidney)
• Non-Hodgkin lymphoma (4%, blood)
• Childhood rhabdomyosarcoma (3%, many sites; a form of rhabdomyosarcoma)
• Retinoblastoma (3%, eye)
• Osteosarcoma (3%, bone cancer)
• Ewing sarcoma (1%, many sites)
• Germ cell tumors (many sites)
• Pleuropulmonary blastoma (lung or pleural cavity)
• Hepatoblastoma and hepatocellular carcinoma (liver cancer)

Epidemiology

Risk factors

Familial and genetic factors are identified in 5-15% of childhood cancer cases. In <5-10% of cases, there are known environmental exposures and exogenous factors, such as prenatal exposure to tobacco, X-rays, or certain medications.^[10] For the remaining 75-90% of cases, however, the individual causes remain unknown.^[10] In most cases, as in carcinogenesis in general, the cancers are assumed to involve multiple risk factors and variables.^[11]

Aspects that make the risk factors of childhood cancer different from those seen in adult cancers include:^[12]

• Different, and sometimes unique, exposures to environmental hazards. Children must often rely on adults to protect them from toxic environmental agents.
• Immature physiological systems to clear or metabolize environmental substances
• The growth and development of children in phases known as "developmental windows" result in certain "critical windows of vulnerability".

Also, a longer life expectancy in children avails for a longer time to manifest cancer processes with long latency periods, increasing the risk of developing some cancer types later in life.^[12]

There are preventable causes of childhood malignancy, such as delivery overuse and misuse of ionizing radiation through computed tomography scans when the test is not indicated or when adult protocols are used.^[13][14]

Incidence and mortality

Internationally, the greatest variation in childhood cancer incidence occurs when comparing high-income countries to low-income ones.^[15] This may result from differences in being able to diagnose cancer, differences in risk among different ethnic or racial population subgroups, as well as differences in risk factors.^[15] An example of differing risk factors is in cases of pediatric Burkitt lymphoma, a form of non-Hodgkin lymphoma that sickens 6 to 7 children out of every 100,000 annually in parts of sub-Saharan Africa, where it is associated with a history of infection by both Epstein-Barr virus and malaria.^[15][16][17] In industrialized countries, Burkitt lymphoma is not associated with these infectious conditions.^[15]

US

In the United States, cancer is the second most common cause of death among children between the ages of 1 and 14 years, exceeded only by accidents.^[8] More than 16 out of every 100,000 children and teens in the U.S. were diagnosed with cancer, and nearly 3 of every 100,000 died from the disease.^[8] In the United States in 2012, it was estimated that there was an incidence of 12,000 new cases, and 1,300 deaths, from cancer among children 0 to 14 years of age.^[18] Statistics from the 2014 American Cancer Society report:

Ages birth to 14^[19]

Ages 15 to 19^[19]

Note: Incidence and mortality rates are per 1,000,000 and age-adjusted to the 2000 US standard population. Observed survival percentage is based on data from 2003-2009.

UK

Cancer is relatively rare in children, accounting for less than 1% of all cancers (around 1,600 children are diagnosed with cancer each year), and it is the leading cause of death in children aged 1–14 (around 250 children die from cancer each year).^[20]

Organizations

Organizations focused on childhood cancer through cancer research and/or support programs include: Childhood Cancer Canada, CLIC Sargent and the Children's Cancer and Leukaemia Group (in the United Kingdom), Child Cancer Foundation (in New Zealand), Children's Cancer Recovery Foundation (in United States), American Childhood Cancer Organization(in the United states),^[21] Childhood Cancer Support (Australia) and the Hayim Association (in Israel).^[22]

The International Childhood Cancer Day occurs annually on February 15.^[5][23]

Learning problems

Children with cancer are at risk for developing various cognitive or learning problems.^[24] These difficulties may be related to brain injury stemming from the cancer itself, such as a brain tumor or central nervous system metastasis or from side effects of cancer treatments such as chemotherapy and radiation therapy. Studies have shown that chemo and radiation therapies may damage brain white matter and disrupt brain activity.

Adult survivors

Adult survivors of childhood cancer have some physical, psychological, and social difficulties.

Premature heart disease is a major long-term complication in adult survivors of childhood cancer.^[25] Adult survivors are eight times more likely to die of heart disease than other people, and more than half of children treated for cancer develop some type of cardiac abnormality, although this may be asymptomatic or too mild to qualify for a clinical diagnosis of heart disease.^[25]

References

1. ↑ EBSCO database verified by URAC; accessed from Mount Sinai Hospital, New York
2. ↑ Bahadur, G. (2000). "Age definitions, childhood and adolescent cancers in relation to reproductive issues". Human Reproduction. 15: 227–221. doi:10.1093/humrep/15.1.227. 
3. 1 2 Childhood Cancers: Basic Facts & Figures from Minnesota Department of Health. Retrieved Dec, 2012
4. ↑ About childhood cancer at Childhood Cancer 2012, by Children With Cancer UK
5. 1 2 3 International Childhood Cancer Day – 15 February 2013 at educationscotland.gov.uk. Retrieved Dec, 2012
6. ↑ Ward EM, Thun MJ, Hannan LM, Jemal A (Sep 2006). "Interpreting cancer trends". Annals of the New York Academy of Sciences. 1076: 29–53. Bibcode:2006NYASA1076...29W. doi:10.1196/annals.1371.048. PMID 17119192. 
7. 1 2 Kaatsch P, Sikora E, Pawelec G (June 2010). "Epidemiology of childhood cancer". Cancer treatment reviews. 36 (4): 277–85. doi:10.1016/j.ctrv.2010.02.003. PMID 20231056. 
8. 1 2 3 4 5 6 Cancer in Children from Centers for Disease Control and Prevention. Page last reviewed: July 30, 2009
9. 1 2 Childhood Cancer overview from American Society of Clinical Oncology (ASCO). Retrieved January 2013
10. 1 2 Children and Cancer, in Children's Health and the Environment, a WHO Training Package for the Health Sector, World Health Organization. In turn citing:
    • Birch JM. Genes & Cancer" Arch Dis Child 1999, 80:1-3.
    • Lichtenstein P et al" N Engl J Med 2000, 13;343(2) 78-85
11. ↑ Children and Cancer, in Children's Health and the Environment, a WHO Training Package for the Health Sector, World Health Organization. In turn citing: Anderson LM et al. Critical Windows of Exposure for Children’s Health: Cancer in Human Epidemiological Studies and Neoplasms in Experimental Animals Models. Environ Health Perspect, 2000, 108(suppl 3) 573-594.
12. 1 2 Children and Cancer, in Children's Health and the Environment, a WHO Training Package for the Health Sector, World Health Organization.
13. ↑ "Radiology Safety - What can I do?". Image Gently. Alliance for Radiation Safety in Pediatric Imaging. Retrieved 8 February 2016. 
14. ↑ Swensen, Stephen; Duncan, James; Gibson, Rosemary (September 2014). "An Appeal for Safe and Appropriate Imaging of Children". Journal of Patient Safety. 10 (3): 121–124. doi:10.1097/PTS.0000000000000116. Retrieved 8 February 2016. 
15. 1 2 3 4 Children and Cancer, in Children's Health and the Environment, a WHO Training Package for the Health Sector, World Health Organization. In turn citing: Scott CH. Childhood cancer epidemiology in low-income countries" Cancer 2007, 112;3:461-472
16. ↑ "Viral Cancers: Epstein-Barr virus". World Health Organization Initiative for Vaccine Research. Retrieved January 28, 2013. 
17. ↑ Moormann AM, Snider CJ, Chelimo K (October 2011). "The company malaria keeps: how co-infection with Epstein-Barr virus leads to endemic Burkitt lymphoma". Current Opinion in Infectious Diseases. 24 (24(5)): 435–41. doi:10.1097/QCO.0b013e328349ac4f. PMID 21885920. 
18. ↑ Cancer Facts & Figures 2011 from American Cancer Society.
19. 1 2 Ward, E; DeSantis, C; Robbins, A; Kohler, B; Jemal, A (Mar–Apr 2014). "Childhood and adolescent cancer statistics, 2014.". CA: A Cancer Journal for Clinicians. 64 (2): 83–103. doi:10.3322/caac.21219. PMID 24488779. 
20. ↑ "Childhood cancer statistics". Cancer Research UK. Retrieved 27 October 2014. 
21. ↑ American Childhood Cancer Organization homepage
22. ↑ "Hayim Association". Retrieved 2016-03-31. 
23. ↑ February 15th is International Childhood Cancer Awareness Day!!! at The Foundation for Children with Cancer (FCC). Retrieved Dec, 2012
24. ↑ Children Diagnosed With Cancer: Returning to School from American Cancer Society. Last Medical Review: 07/02/2012
25. 1 2 Lipshultz, Steven E.; Franco, Vivian I.; Miller, Tracie L.; Colan, Steven D.; Sallan, Stephen E. (2015-01-01). "Cardiovascular Disease in Adult Survivors of Childhood Cancer". Annual Review of Medicine. 66 (1): 161–176. doi:10.1146/annurev-med-070213-054849. PMID 25587648. 

 This article incorporates public domain material from the Centers for Disease Control and Prevention website http://www.cdc.gov/.