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National Cancer Institute Fact Sheet
    Reviewed: 01/10/2008
Childhood Cancers: Questions and Answers

Key Points

  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 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.

  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).

    • 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, non-Hodgkin 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 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 is available at http://www.stjude.org/stjude/v/index.jsp?vgnextoid=0d5dd3ce38e70110VgnVCM100
    0001e0215acRCRD&vgnextchannel=cc66c08e1f5d3110VgnVCM1000001e0215acRCRD 1on 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 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..

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Glossary Terms

abnormal
Not normal. An abnormal lesion or growth may be cancerous, premalignant (likely to become cancer), or benign.
acquired immunodeficiency syndrome (uh-KWY-erd IH-myoo-noh-dih-FIH-shun-see SIN-drome)
AIDS. A disease caused by human immunodeficiency virus (HIV). People with acquired immunodeficiency syndrome are at an increased risk for developing certain cancers and for infections that usually occur only in individuals with a weak immune system. Also called AIDS.
acute lymphoblastic leukemia (...LIM-foh-BLAS-tik loo-KEE-mee-uh)
ALL. A fast-growing type of leukemia (blood cancer) in which too many lymphoblasts (immature white blood cells) are found in the blood and bone marrow. Also called ALL and acute lymphocytic leukemia.
acute myeloid leukemia (uh-KYOOT MY-eh-loyd loo-KEE-mee-uh)
A quickly progressing disease in which too many immature white blood cells (not lymphocytes) are found in the blood and bone marrow. Also called AML, acute myelogenous leukemia, acute myeloblastic leukemia, acute nonlymphocytic leukemia, and ANLL.
alkylating agent
A drug that is used in the treatment of cancer. It interferes with the cell's DNA and inhibits cancer cell growth.
animal model
An animal with a disease either the same as or like a disease in humans. Animal models are used to study the development and progression of diseases and to test new treatments before they are given to humans. Animals with transplanted human cancers or other tissues are called xenograft models.
antibody (AN-tee-BAH-dee)
A type of protein made by plasma cells (a type of white blood cell) in response to an antigen (foreign substance). Each antibody can bind to only one specific antigen. The purpose of this binding is to help destroy the antigen. Antibodies can work in several ways, depending on the nature of the antigen. Some antibodies destroy antigens directly. Others make it easier for white blood cells to destroy the antigen.
astrocytoma (AS-troh-sy-TOH-muh)
A tumor that begins in the brain or spinal cord in small, star-shaped cells called astrocytes.
benign (beh-NINE)
Not cancerous. Benign tumors may grow larger but do not spread to other parts of the body.
biological (BY-oh-LAH-jih-kul)
Pertaining to biology or to life and living things. In medicine, refers to a substance made from a living organism or its products. Biologicals may be used to prevent, diagnose, treat or relieve of symptoms of a disease. For example, antibodies, interleukins, and vaccines are biologicals. Biological also refers to parents and children who are related by blood.
blood
A tissue with red blood cells, white blood cells, platelets, and other substances suspended in fluid called plasma. Blood takes oxygen and nutrients to the tissues, and carries away wastes.
bone marrow transplantation (bone MAYR-oh tranz-plan-TAY-shun)
A procedure to replace bone marrow that has been destroyed by treatment with high doses of anticancer drugs or radiation. Transplantation may be autologous (an individual's own marrow saved before treatment), allogeneic (marrow donated by someone else), or syngeneic (marrow donated by an identical twin).
brain tumor
The growth of abnormal cells in the tissues of the brain. Brain tumors can be benign (non-cancerous) or malignant (cancerous).
cancer (KAN-ser)
A term for diseases in which abnormal cells divide without control. Cancer cells can invade nearby tissues and can spread to other parts of the body through the blood and lymph systems. There are several main types of cancer. Carcinoma is cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood. Lymphoma and multiple myeloma are cancers that begin in the cells of the immune system. Central nervous system cancers are cancers that begin in the tissues of the brain and spinal cord.
cell (sel)
The individual unit that makes up the tissues of the body. All living things are made up of one or more cells.
central nervous system (SEN-trul NER-vus SIS-tem)
CNS. The brain and spinal cord. Also called CNS.
chemotherapy (KEE-moh-THAYR-uh-pee)
Treatment with drugs that kill cancer cells.
clinical study
A type of research study that tests how well new medical approaches work in people. These studies test new methods of screening, prevention, diagnosis, or treatment of a disease. Also called a clinical trial.
clinical trial
A type of research study that tests how well new medical approaches work in people. These studies test new methods of screening, prevention, diagnosis, or treatment of a disease. Also called a clinical study.
cure
To heal or restore health; a treatment to restore health.
diagnosis (DY-ug-NOH-sis)
The process of identifying a disease, such as cancer, from its signs and symptoms.
diet
The things a person eats and drinks.
Down syndrome (...SIN-drome)
A disorder caused by the presence of an extra chromosome 21 and characterized by mental retardation and distinguishing physical features.
drug
Any substance, other than food, that is used to prevent, diagnose, treat or relieve symptoms of a disease or abnormal condition. Also refers to a substance that alters mood or body function, or that can be habit-forming or addictive, especially a narcotic.
epidemiology (EH-pih-dee-mee-AH-loh-jee)
The study of the patterns, causes, and control of disease in groups of people.
fertility (fer-TIL-i-tee)
The ability to produce children.
genetic (jeh-NEH-tik)
Inherited; having to do with information that is passed from parents to offspring through genes in sperm and egg cells.
genetic susceptibility
An inherited increase in the risk of developing a disease. Also called genetic predisposition.
germ cell tumor (jurm sel TOO-mer)
A type of tumor that begins in the cells that give rise to sperm or eggs. Germ cell tumors can occur almost anywhere in the body and can be either benign or malignant.
glioma (glee-OH-muh)
A cancer of the brain that begins in glial cells (cells that surround and support nerve cells).
Gorlin syndrome
A genetic condition that causes unusual facial features and disorders of the skin, bones, nervous system, eyes, and endocrine glands. People with this syndrome have a higher risk of basal cell carcinoma. Also called nevoid basal cell carcinoma syndrome and basal cell nevus syndrome.
human immunodeficiency virus (HYOO-mun ih-MYOO-noh-dih-FIH-shun-see VY-rus)
HIV. The cause of acquired immunodeficiency syndrome (AIDS). Also called HIV.
imaging (IH-muh-jing)
In medicine, a process that makes pictures of areas inside the body. Imaging uses methods such as x-rays (high-energy radiation), ultrasound (high-energy sound waves), and radio waves.
immune system (ih-MYOON SIS-tem)
The complex group of organs and cells that defends the body against infections and other diseases.
immunotherapy (IH-myoo-noh-THAYR-uh-pee)
Treatment to boost or restore the ability of the immune system to fight cancer, infections, and other diseases. Also used to lessen certain side effects that may be caused by some cancer treatments. Agents used in immunotherapy include monoclonal antibodies, growth factors, and vaccines. These agents may also have a direct antitumor effect. Also called biological therapy, biotherapy, biological response modifier therapy, and BRM therapy.
immunotoxin (IH-myoo-noh-TOK-sin)
An antibody linked to a toxic substance. Some immunotoxins can bind to cancer cells and kill them.
incidence
The number of new cases of a disease diagnosed each year.
invasive cancer (in-VAY-siv KAN-ser)
Cancer that has spread beyond the layer of tissue in which it developed and is growing into surrounding, healthy tissues. Also called infiltrating cancer.
ionizing radiation (I-uh-NYZ-ing RAY-dee-AY-shun)
A type of radiation made (or given off ) by x-ray procedures, radioactive substances, rays that enter the Earth's atmosphere from outer space, and other sources. At high doses, ionizing radiation increases chemical activity inside cells and can lead to health risks, including cancer.
Kaposi sarcoma (kuh-POH-zee sar-KOH-muh)
A type of cancer characterized by the abnormal growth of blood vessels that develop into skin lesions or occur internally.
leiomyosarcoma (LY-oh-MY-oh-sar-KOH-muh)
A malignant (cancerous) tumor of smooth muscle cells that can arise almost anywhere in the body, but is most common in the uterus, abdomen, or pelvis.
leukemia (loo-KEE-mee-uh)
Cancer that starts in blood-forming tissue such as the bone marrow and causes large numbers of blood cells to be produced and enter the bloodstream.
Li-Fraumeni syndrome
A rare, inherited predisposition to multiple cancers, caused by an alteration in the p53 tumor suppressor gene.
magnetic resonance imaging (mag-NEH-tik REH-zuh-nunts IH-muh-jing)
A procedure in which radio waves and a powerful magnet linked to a computer are used to create detailed pictures of areas inside the body. These pictures can show the difference between normal and diseased tissue. Magnetic resonance imaging makes better images of organs and soft tissue than other scanning techniques, such as computed tomography (CT) or x-ray. Magnetic resonance imaging is especially useful for imaging the brain, the spine, the soft tissue of joints, and the inside of bones. Also called MRI, nuclear magnetic resonance imaging, and NMRI.
malignant (muh-LIG-nunt)
Cancerous. Malignant tumors can invade and destroy nearby tissue and spread to other parts of the body.
medulloblastoma (MED-yoo-loh-blas-TOH-muh)
A malignant brain tumor that begins in the lower part of the brain and that can spread to the spine or to other parts of the body. Medulloblastomas are a type of primitive neuroectodermal tumor (PNET).
National Cancer Institute
The National Cancer Institute, part of the National Institutes of Health of the United States Department of Health and Human Services, is the Federal Government's principal agency for cancer research. The National Cancer Institute conducts, coordinates, and funds cancer research, training, health information dissemination, and other programs with respect to the cause, diagnosis, prevention, and treatment of cancer. Access the National Cancer Institute Web site at http://www.cancer.gov. Also called NCI.
National Institutes of Health
NIH. A federal agency in the U.S. that conducts biomedical research in its own laboratories; supports the research of non-Federal scientists in universities, medical schools, hospitals, and research institutions throughout the country and abroad; helps in the training of research investigators; and fosters communication of medical information. Access the National Institutes of Health Web site at http://www.nih.gov. Also called NIH.
neoplasia (NEE-oh-PLAY-zhuh)
Abnormal and uncontrolled cell growth.
neuroblastoma (NOOR-oh-blas-TOH-muh)
Cancer that arises in immature nerve cells and affects mostly infants and children.
neurofibromatosis type 1 (NOOR-oh-FY-broh-muh-TOH-sis tipe 1)
NF1. A rare genetic condition that causes brown spots and tumors on the skin, freckling in skin areas not exposed to the sun, tumors on the nerves, and developmental changes in the nervous system, muscles, bone, and skin. Also called NF1.
non-Hodgkin lymphoma (non-HOJ-kin lim-FOH-muh)
Any of a large group of cancers of the immune system. Non-Hodgkin lymphomas can occur at any age and are often marked by enlarged lymph nodes, fever, and weight loss. There are many different types of non-Hodgkin lymphoma, which can be divided into aggressive (fast-growing) and indolent (slow-growing) types and can be classified as either B-cell or T-cell non-Hodgkin lymphoma. B-cell non-Hodgkin lymphomas include Burkitt lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, immunoblastic large cell lymphoma, precursor B-lymphoblastic lymphoma, and mantle cell lymphoma. T-cell non-Hodgkin lymphomas include mycosis fungoides, anaplastic large cell lymphoma, and precursor T-lymphoblastic lymphoma. Lymphomas related to lymphoproliferative disorders following bone marrow or stem cell transplantation are usually B-cell non-Hodgkin lymphomas. Prognosis and treatment depend on the stage and type of disease. Also called NHL.
oncology (on-KAH-loh-jee)
The study of cancer.
osteosarcoma (OS-tee-oh-sar-KOH-muh)
A cancer of the bone that usually affects the large bones of the arm or leg. It occurs most commonly in young people and affects more males than females. Also called osteogenic sarcoma.
pediatric (pee-dee-A-trik)
Having to do with children.
phase I trial
The first step in testing a new treatment in humans. These studies test the best way to give a new treatment (for example, by mouth, intravenous infusion, or injection) and the best dose. The dose is usually increased a little at a time in order to find the highest dose that does not cause harmful side effects. Because little is known about the possible risks and benefits of the treatments being tested, phase I trials usually include only a small number of patients who have not been helped by other treatments.
phase II trial
A study to test whether a new treatment has an anticancer effect (for example, whether it shrinks a tumor or improves blood test results) and whether it works against a certain type of cancer.
phase III trial
A study to compare the results of people taking a new treatment with the results of people taking the standard treatment (for example, which group has better survival rates or fewer side effects). In most cases, studies move into phase III only after a treatment seems to work in phases I and II. Phase III trials may include hundreds of people.
pilot study
The initial study examining a new method or treatment.
preclinical study
Research using animals to find out if a drug, procedure, or treatment is likely to be useful. Preclinical studies take place before any testing in humans is done.
radiation (RAY-dee-AY-shun)
Energy released in the form of particle or electromagnetic waves. Common sources of radiation include radon gas, cosmic rays from outer space, medical x-rays, and energy given off by a radioisotope (unstable form of a chemical element that releases radiation as it breaks down and becomes more stable).
radiation therapy (RAY-dee-AY-shun THAYR-uh-pee)
The use of high-energy radiation from x-rays, gamma rays, neutrons, protons, and other sources to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beam radiation therapy), or it may come from radioactive material placed in the body near cancer cells (internal radiation therapy). Systemic radiation therapy uses a radioactive substance, such as a radiolabeled monoclonal antibody, that travels in the blood to tissues throughout the body. Also called radiotherapy and irradiation.
radiotherapy (RAY-dee-oh-THAYR-uh-pee)
The use of high-energy radiation from x-rays, gamma rays, neutrons, protons, and other sources to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beam radiation therapy), or it may come from radioactive material placed in the body near cancer cells (internal radiation therapy). Systemic radiotherapy uses a radioactive substance, such as a radiolabeled monoclonal antibody, that travels in the blood to tissues throughout the body. Also called radiation therapy and irradiation.
radon (RAY-don)
A radioactive gas that is released by uranium, a substance found in soil and rock. Breathing in too much radon can damage lung cells and may lead to lung cancer.
regimen
A treatment plan that specifies the dosage, the schedule, and the duration of treatment.
remission
A decrease in or disappearance of signs and symptoms of cancer. In partial remission, some, but not all, signs and symptoms of cancer have disappeared. In complete remission, all signs and symptoms of cancer have disappeared, although cancer still may be in the body.
rhabdomyosarcoma (RAB-doh-MY-oh-sar-KOH-muh)
Cancer that forms in the soft tissues in a type of muscle called striated muscle. Rhabdomyosarcoma can occur anywhere in the body.
risk factor
Something that may increase the chance of developing a disease. Some examples of risk factors for cancer include age, a family history of certain cancers, use of tobacco products, certain eating habits, obesity, lack of exercise, exposure to radiation or other cancer-causing agents, and certain genetic changes.
sarcoma
A cancer of the bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue.
second primary cancer
Refers to a new primary cancer in a person with a history of cancer.
solid tumor
An abnormal mass of tissue that usually does not contain cysts or liquid areas. Solid tumors may be benign (not cancerous), or malignant (cancerous). Different types of solid tumors are named for the type of cells that form them. Examples of solid tumors are sarcomas, carcinomas, and lymphomas. Leukemias (cancers of the blood) generally do not form solid tumors.
syndrome (SIN-drome)
A set of symptoms or conditions that occur together and suggest the presence of a certain disease or an increased chance of developing the disease.
therapeutic (THAYR-uh-PYOO-tik)
Having to do with treating disease and helping healing take place.
therapy (THAYR-uh-pee)
Treatment.
toxic (TOK-sik)
Having to do with poison or something harmful to the body. Toxic substances usually cause unwanted side effects.
toxicity (tok-SIH-sih-tee)
The extent to which something is poisonous or harmful.
toxin (TOK-sin)
A poison produced by certain animals, plants, or bacteria.
tumor (TOO-mer)
An abnormal mass of tissue that results when cells divide more than they should or do not die when they should. Tumors may be benign (not cancerous), or malignant (cancerous). Also called neoplasm.
ultrasound (UL-truh-SOWND)
A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echo patterns are shown on the screen of an ultrasound machine, forming a picture of body tissues called a sonogram. Also called ultrasonography.
virus (VY-rus)
In medicine, a very simple microorganism that infects cells and may cause disease. Because viruses can multiply only inside infected cells, they are not considered to be alive.


Table of Links

1http://www.stjude.org/stjude/v/index.jsp?vgnextoid=0d5dd3ce38e70110VgnVCM100000
1e0215acRCRD&vgnextchannel=cc66c08e1f5d3110VgnVCM1000001e0215acRCRD
2http://cancer.gov/cancertopics/factsheet/NCI/children-adolescents
3http://cancer.gov/cancertopics/factsheet/Information/clinical-trials