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Childhood Cancers: Questions and Answers 

1. What are the most common types of childhood cancer? 

Among the 12 major types of childhood cancers, leukemias (blood cell cancers) and 

cancers of the brain and central nervous system account for more than half of the new 

cases. About one-third of childhood cancers are leukemias. The most common type of 

leukemia in children is acute lymphoblastic leukemia. The most common solid tumors 

are brain tumors (e.g., gliomas and medulloblastomas), with other solid tumors (e.g., 

neuroblastomas, Wilms tumors, and sarcomas such as rhabdomyosarcoma and 

osteosarcoma) being less common. 

2. How many children are diagnosed with cancer in the United States annually? 

In the United States in 2007, approximately 10,400 children under age 15 were diagnosed 

with cancer and about 1,545 children will die from the disease (1). Although this makes 

cancer the leading cause of death by disease among U.S. children 1 to 14 years of age, 

cancer is still relatively rare in this age group. On average, 1 to 2 children develop the 

disease each year for every 10,000 children in the United States (2). 

3. How have childhood cancer incidence and survival rates changed over the years? 

Over the past 20 years, there has been some increase in the incidence of children 

diagnosed with all forms of invasive cancer, from 11.5 cases per 100,000 children in 

1975 to 14.8 per 100,000 children in 2004. During this same time, however, death rates 

Key Points 

• Leukemias and cancers of the brain and central nervous system account 

for more than half of childhood cancers (see Question 1). 

• The causes of childhood cancers are largely unknown (see Question 4). 

• The National Cancer Institute is funding studies examining the causes of 

and the most effective treatments for childhood cancers (see Question 6). 
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declined dramatically and 5-year survival rates increased for most childhood cancers. 

For example, the 5-year survival rates for all childhood cancers combined increased from 

58.1 percent in 1975–77 to 79.6 percent in 1996–2003 (2). This improvement in survival 

rates is due to significant advances in treatment, resulting in a cure or long-term 

remission for a substantial proportion of children with cancer. 

Long-term trends in incidence for leukemias and brain tumors, the most common 

childhood cancers, show patterns that are somewhat different from the others. Incidence 

of childhood leukemias appeared to rise in the early 1980s, with rates increasing from 3.3 

cases per 100,000 in 1975 to 4.6 cases per 100,000 in 1985. Rates in the succeeding 

years have shown no consistent upward or downward trend and have ranged from 3.7 to 

4.9 cases per 100,000 (2). 

For childhood brain tumors, the overall incidence rose from 1975 through 2004, from 

2.3 to 3.2 cases per 100,000 (2), with the greatest increase occurring from l983 through 

l986. An article in the September 2, 1998, issue of the Journal of the National Cancer 

Institute suggests that the rise in incidence from 1983 through 1986 may not have 

represented a true increase in the number of cases, but may have reflected new forms of 

imaging equipment (magnetic resonance imaging or MRI) that enabled visualization of 

brain tumors that could not be easily visualized with older equipment (3). Other 

important developments during this time period included the changing classification of 

brain tumors, which resulted in tumors previously designated as “benign” being 

reclassified as “malignant,” and improvements in neurosurgical techniques for biopsying 

brain tumors. Regardless of the explanation for the increase in incidence that occurred 

from 1983 to 1986, childhood brain tumor incidence has been essentially stable since the 

mid-1980s. 

A monograph based on data from the National Cancer Institute’s (NCI) Surveillance, 

Epidemiology, and End Results (SEER) Program was published in 1999 on U.S. trends in 

incidence, mortality, and survival rates of childhood cancers. This monograph, Cancer 

Incidence and Survival Among Children and Adolescents: United States SEER Program 

1975–1995, is available at http://seer.cancer.gov/publications/childhood/ on the Internet. 

In 2006, SEER published another monograph, Cancer Epidemiology in Older 

Adolescents and Young Adults 15 to 29 Years of Age, Including SEER Incidence and 

Survival: 1975–2000. This monograph is the first to collect detailed information about 

cancer incidence and outcomes in adolescents and young adults (AYA). It provides 

population-based incidence, mortality, and survival data specific to cancers that occur in 

the AYA population, along with epidemiological data and risk factors for the 

development of age-specific cancers. This resource is available at 

http://seer.cancer.gov/publications/aya/ on the Internet. More recent cancer statistics for 

children ages 0–14 and 0–19 are available in sections 28 and 29 of the SEER Cancer 

Statistics Review, 1975–2004 at http://seer.cancer.gov/csr/1975_2004/sections.html on 

the Internet. 
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4. What are the known or suspected causes of childhood cancer? 

The causes of childhood cancers are largely unknown. A few conditions, such as Down 

syndrome, other specific chromosomal and genetic abnormalities, and ionizing radiation 

exposures, explain a small percentage of cases. 

Environmental causes of childhood cancer have long been suspected by many scientists 

but have been difficult to pin down, partly because cancer in children is rare and because 

it is difficult to identify past exposure levels in children, particularly during potentially 

important periods such as pregnancy or even prior to conception. In addition, each of the 

distinctive types of childhood cancers develops differently—with a potentially wide 

variety of causes and a unique clinical course in terms of age, race, gender, and many 

other factors. Possible risk factors for specific childhood cancers are discussed in the 

SEER monograph mentioned above. It can be found at 

http://seer.cancer.gov/publications/childhood/ on the Internet. 

A number of studies are examining suspected or possible risk factors for childhood 

cancers, including early-life exposures to infectious agents; parental, fetal, or childhood 

exposures to environmental toxins such as pesticides, solvents, or other household 

chemicals; parental occupational exposures to radiation or chemicals; parental medical 

conditions during pregnancy or before conception; maternal diet during pregnancy; early 

postnatal feeding patterns and diet; and maternal reproductive history. Researchers are 

also studying the risks associated with maternal exposures to oral contraceptives, fertility 

drugs, and other medications; familial and genetic susceptibility; and risk associated with 

exposure to the human immunodeficiency virus (HIV). 

5. What have studies shown about the possible causes of childhood cancer? 

For several decades, the NCI, a part of the National Institutes of Health (NIH), has 

supported national and international collaborations devoted to studying the causes of 

cancer in children. Key findings from this research include the following: 

• High levels of ionizing radiation from accidents or from radiotherapy have been 

linked with increased risk of some childhood cancers. 

• Children with cancer treated with chemotherapy and/or radiation therapy may be at 

increased risk for developing a second primary cancer. For example, certain types of 

chemotherapy, including alkylating agents or topoisomerase II inhibitors (e.g., 

epipodophyllotoxins), can cause an increased risk of leukemia. 

• Recent research has shown that children with AIDS (acquired immunodeficiency 

syndrome), like adults with AIDS, have an increased risk of developing certain 

cancers, predominantly non-Hodgkin lymphoma and Kaposi sarcoma. These 

children also have an additional risk of developing leiomyosarcoma (a type of 

muscle cancer). 
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• Certain genetic syndromes (e.g., Li-Fraumeni syndrome, neurofibromatosis, and 

Gorlin syndrome) have been linked to an increased risk of specific childhood 

cancers. 

• Children with Down syndrome have an increased risk of developing leukemia. 

• Low levels of radiation exposure from indoor radon have not been significantly 

associated with childhood leukemias. 

• Ultrasound use during pregnancy has not been linked with childhood cancer in 

numerous large studies. 

• Residential magnetic field exposure from power lines has not been significantly 

associated with childhood leukemias. 

• Pesticides have been suspected to be involved in the development of certain forms of 

childhood cancer based on interview data. However, interview results have been 

inconsistent and have not yet been validated by physical evidence of pesticides in the 

child’s body or environment. 

• No consistent findings have been observed linking specific occupational exposures 

of parents to the development of childhood cancers. 

• Several studies have found no link between maternal cigarette smoking before 

pregnancy and childhood cancers, but increased risks have been related to the 

father’s smoking habits in studies in the United Kingdom and China. 

• Little evidence has been found to link specific viruses or other infectious agents to 

the development of most types of childhood cancers, though investigators worldwide 

are exploring the role of exposures of very young children to some common 

infectious agents that may protect children from, or put them at risk for, developing 

certain leukemias. 

6. What research is NCI currently doing on childhood cancer? 

The NCI is funding a large portfolio of studies (http://researchportfolio.cancer.gov/) 

looking at the causes of and the most effective treatments for childhood cancers. 

Ongoing investigations include: 

• Studies to identify causes of the cancers that develop in children: The Children’s 

Oncology Group (COG) (http://www.childrensoncologygroup.org) is evaluating 

potential risk factors for a variety of childhood cancers. Very large studies have been 

completed of childhood acute lymphoblastic leukemia, acute myeloid leukemia, nonHodgkin lymphoma, primitive neuroectodermal tumors of the brain, astrocytoma, 

neuroblastoma, and germ cell tumors. One large study, the Childhood Cancer 

Survivor Study, is evaluating the risks of second cancers related to radiation therapy 
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and chemotherapy received by survivors of childhood cancer as part of treatment for 

their primary cancer (see below). 

COG has also established a Childhood Cancer Research Network that creates a 

national registry of children with cancer. This initiative builds upon the unique 

NCI-supported national clinical trials system for treating children with cancer. 

• Monitoring of U.S. and international trends in incidence and mortality rates for 

childhood cancers: By identifying places where high or low cancer rates occur, 

researchers can uncover patterns of cancer that provide important clues for further 

in-depth studies into the causes and control of cancer.

• Studies to better understand the biology of childhood cancer, with the hope that 

this understanding will lead to new treatment approaches that target critical 

cellular processes required for cancer cell growth and survival: The Childhood 

Cancer Therapeutically Applicable Research to Generate Effective Treatments 

(TARGET) Initiative was established by the NCI and the Foundation for the National 

Institutes of Health to identify and validate therapeutic targets in childhood cancers. 

The first TARGET project focuses on targets for high-risk acute lymphoblastic 

leukemia and the second TARGET project focuses on neuroblastoma. More 

information about the TARGET Initiative can be found in the article “Initiative 

TARGETs Childhood Cancer” at

http://www.cancer.gov/NCICancerBulletin/NCI_Cancer_Bulletin_112106 on the 

Internet.

• Preclinical studies (animal studies) of new agents to identify promising 

anticancer drugs that can be evaluated in clinical trials: The NCI-supported 

Pediatric Preclinical Testing Program (PPTP) systematically evaluates new drugs and 

substances using animal models (animals with a cancer similar to or the same as a 

cancer found in children) to find the drugs most likely to have significant anticancer 

effects in clinical trials. The program is based on a large amount of research showing 

that animal models imitate the effects of proven anticancer drugs and can be used to 

prospectively identify new drugs that are effective against childhood cancers in 

subsequent patient studies. More information about the PPTP is available at 

http://pptp.stjude.org/ on the Internet. Questions concerning the PPTP can be 

addressed to the PPTP Project Officer, Dr. Malcolm Smith 

(smithm@ctep.nci.nih.gov).

• Projects designed to improve the health status of survivors of childhood 

cancers: The NCI funds the Childhood Cancer Survivor Study (CCSS), a study 

coordinated by St. Jude Children’s Research Hospital. The CCSS has over 25 sites 

across the country at medical institutions with doctors specializing in long-term care 

for children and young adults. This study was created to gain new knowledge and to 

educate cancer survivors about the long-term effects of cancer and cancer treatment. 

Information about the study, including access to a list of participating institutions, is 

available at 

http://www.stjude.org/stjude/v/index.jsp?vgnextoid=0d5dd3ce38e70110VgnVCM100
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001e0215acRCRD&vgnextchannel=448d0817933fe010VgnVCM1000005f2015acR

CRD on the Internet. 

• Clinical trials to identify superior treatments for childhood cancers, thereby 

leading to improved survival rates for children with cancer: Each year about 

4,000 children enter 1 of approximately 100 ongoing clinical trials sponsored by the 

NCI. The following groups are conducting these trials:

The COG, with support from the NCI, conducts clinical trials devoted exclusively to 

children and adolescents with cancer at more than 200 member institutions, including 

cancer centers of all major universities, teaching hospitals throughout the United 

States and Canada, and sites in Europe and Australia. COG was formed in 2000 by 

the merger of four children’s cancer cooperative groups to accelerate the search for a 

cure for childhood cancers and to make it possible for children with cancer, regardless 

of where they live, to have access to state-of-the-art therapies and the collective 

expertise of world-renowned pediatric specialists. 

The Pediatric Brain Tumor Consortium (PBTC) (http://www.pbtc.org) includes 10 

leading academic institutions with extensive experience in the design and conduct of 

clinical trials for children with brain tumors. The group’s primary objective is to 

rapidly conduct phase I and II clinical evaluations of new therapeutic drugs, treatment 

delivery technologies, new biological therapies, and radiation treatment strategies in 

children up to age 21 with primary central nervous system (CNS) tumors. Another 

objective of the PBTC is to develop and coordinate innovative neuroimaging 

techniques. Results from PBTC studies are made available to large international 

collaborative groups for confirmatory phase II and multiagent phase III clinical trials. 

New Approaches to Neuroblastoma Therapy (NANT) (http://www.nant.org) is a 

consortium of university and children’s hospitals funded by the NCI to test promising 

new therapies for neuroblastoma. NANT members constitute a group of closely 

collaborating investigators linked with laboratory programs where novel therapies for 

high-risk neuroblastoma are being developed. The group conducts early clinical trials 

to test new drugs and new combinations of drugs so promising therapies can be tested 

nationally. 

The Pediatric Oncology Branch (POB) 

(http://home.ccr.cancer.gov/oncology/pediatric/) of the NCI’s Center for Cancer 

Research conducts basic, preclinical, and clinical studies of childhood cancer at the 

NIH Clinical Center in Bethesda, MD. Basic studies include analyses of genetic and 

biological characteristics of childhood cancers, as well as the study of immune system 

interactions with these cancers and the effects of chemotherapy on the immune 

system. Preclinical studies by the POB identify new drugs and types of 

immunotherapy (treatment to boost the immune system’s ability to fight cancer), as 

well as agents to control infectious diseases that occur in childhood cancer patients. 

An active clinical trial program includes phase I and phase II studies of new agents to 

treat childhood cancers, with a focus on molecularly targeted therapy and 

immunotherapy, as well as bone marrow transplantation and the development of 

immunotoxins (antibodies linked to a toxic substance that bind to cancer cells and kill 
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them) to treat childhood leukemia. The POB also develops and tests new treatments 

for tumors associated with genetic predisposition syndromes such as 

neurofibromatosis type 1 and multiple endocrine neoplasia. 

• Evaluations of new drugs that may be more effective against childhood cancers 

and that may have less toxicity for children: The COG Phase I/Pilot Consortium is 

a major component of the NCI’s pediatric drug development program. The primary 

objective of the consortium is to develop and implement pediatric phase I and pilot 

studies to promote the integration of advances in cancer biology and therapy into the 

treatment of childhood cancer. The consortium includes approximately 20 

institutions that carefully monitor the drugs for toxicity and safety. After their initial 

evaluation for safety in children by the consortium, the agents and regimens can then 

be studied within the larger group of COG institutions to determine their role in the 

treatment of specific childhood cancers. 

Selected References 

1. American Cancer Society. Cancer Facts and Figures 2007. Atlanta, GA: American 

Cancer Society. Retrieved December 26, 2007, from 

http://www.cancer.org/downloads/STT/CAFF2007PWSecured.pdf. 

2. Ries LAG, Melbert D, Krapcho M, et al. SEER Cancer Statistics Review, 1975–2004. 

Bethesda, MD: National Cancer Institute. Retrieved December 26, 2007, from 

http://seer.cancer.gov/csr/1975_2004. 

3. Smith MA, Freidlin B, Ries LA, Simon R. Trends in reported incidence of primary 

malignant brain tumors in children in the United States. Journal of the National Cancer 

Institute 1998; 90(17):1269–1277. 

# # # 

Related NCI materials and Web pages: 

• National Cancer Institute Fact Sheet 1.21, Care for Children and Adolescents With 

Cancer: Questions and Answers 

(http://www.cancer.gov/cancertopics/factsheet/NCI/children-adolescents) 

• National Cancer Institute Fact Sheet 2.11, Clinical Trials: Questions and Answers 

(http://www.cancer.gov/cancertopics/factsheet/Information/clinical-trials)

• Childhood Cancers Home Page 

(http://www.cancer.gov/cancertopics/types/childhoodcancers)

For more help, contact: 

NCI’s Cancer Information Service 

Telephone (toll-free): 1–800–4–CANCER (1–800–422–6237) 
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TTY (toll-free): 1–800–332–8615

LiveHelp® online chat: https://cissecure.nci.nih.gov/livehelp/welcome.asp

This fact sheet was reviewed on 1/10/08