Cancer in Children and Adolescents
How common is cancer in children?
Although cancer in children is rare, it is the leading cause of death by disease past infancy among children in the United States. In 2018, it is estimated that 15,590 children and adolescents ages 0 to 19 will be diagnosed with cancer and 1,780 will die of the disease in the United States (1). Among children ages 0 to 14 years, it is estimated that, in 2018, 10,590 will be diagnosed with cancer and 1,180 will die of the disease (1). Among adolescents ages 15 to 19 years, about 5000 will be diagnosed with cancer and about 600 will die of the disease.
Overall, among children and adolescents (ages 0 to 19) in the United States, the most common types of cancer are leukemias, brain and central nervous system tumors, and lymphomas. Among children (ages 0 to 14 years), the most common types of cancer are leukemias, followed by brain and other central nervous system tumors, lymphomas, soft tissue sarcomas (of which half are rhabdomyosarcoma), neuroblastoma, and kidney tumors (1). Among adolescents (ages 15 to 19 years), the most common types of cancer are brain and other central nervous system tumors and lymphomas, followed by leukemias, gonadal (testicular and ovarian) germ cell tumors, thyroid cancer, and melanoma (1).
As of January 1, 2015 (the most recent date for which data exist), approximately 429,000 survivors of childhood and adolescent cancer (diagnosed at ages 0 to 19 years) were alive in the United States (2). The number of survivors will continue to increase, given that the incidence of childhood cancer has been rising slightly in recent decades and that survival rates overall are improving.
What is the outlook for children and adolescents with cancer?
The overall outlook for children and adolescents with cancer has improved greatly over the last half-century. In the mid-1970s, 58% of children (ages 0 to 14 years) and 68% of adolescents (ages 15 to 19 years) diagnosed with cancer survived at least 5 years (1). In 2008–2014, 83.4% of children and 84.6% of adolescents diagnosed with cancer survived at least 5 years (2).
Although survival rates for most childhood cancers have improved in recent decades, the improvement has been especially dramatic for a few cancers, particularly acute lymphoblastic leukemia, which is the most common childhood cancer. Improved treatments introduced beginning in the 1960s and 1970s raised the 5-year survival rate for children diagnosed with acute lymphoblastic leukemia at ages 0 to 14 years from 57% in 1975 to 92% in 2012 (3). The 5-year survival rate for children diagnosed with non-Hodgkin lymphoma at ages 0 to 14 years has also increased dramatically, from 43% in 1975 to 91% in 2012 (3).
Because of these survival improvements, in more recent years brain cancer has replaced leukemia as the leading cause of cancer death among children (4).
By contrast, survival rates remain very low for some cancer types, for some age groups, and for some cancers within a site. For example, half of children with diffuse intrinsic pontine glioma (a type of brain tumor) survive less than 1 year from diagnosis (5). Among children with Wilms tumor (a type of kidney cancer), older children (those diagnosed between ages 10 and 16 years) have lower 5-year survival rates than younger children (6). For soft tissue sarcomas, 5-year survival rates in 2008–2014 among children and adolescents ages 0 to 19 years ranged from 65% (rhabdomyosarcoma) to 95% (chondrosarcoma) (7), but children with sarcomas who present with metastatic disease have much lower 5-year survival rates. And the 5-year survival rate for acute lymphoblastic leukemia in 2008-2014 was 91% for children younger than 15 years, compared with 74% for adolescents ages 15 to 19 years (7).
Some evidence suggests that adolescents and young adults with acute lymphoblastic leukemia may have better outcomes if they are treated with pediatric treatment regimens than if they receive adult treatment regimens (8). The improvement in 5-year survival rates for 15- to 19-year-olds with acute lymphoblastic leukemia may reflect greater use of these pediatric treatment regimens.
The cancer mortality rate—the number of deaths due to cancer per 100,000 people per year—among children and adolescents ages 0 to 19 years declined by more than 50% from 1975 to 2015 (2). Specifically, the mortality rate was 5.1 per 100,000 children and adolescents in 1975 and 2.3 per 100,000 children and adolescents in 2015. However, despite the overall decrease in mortality, approximately 1,800 children and adolescents still die of cancer each year in the United States, indicating that new advances and continued research to identify effective treatments are required to further reduce childhood cancer mortality.
Between 1999 and 2014, the cancer death rate dropped the most for 1- to-4-year-olds (a 26% drop), followed by that for 15- to 19-year-olds (a 22% drop), 10- to 14-year-olds (a 19% drop), and 5- to 9-year-olds (a 14% drop) (4).
What are the possible causes of cancer in children?
The causes of most childhood cancers are not known. Up to 10% of all cancers in children are caused by a heritable (germline) mutation (a mutation that can be passed from parents to their children). For example, about 45% of children with retinoblastoma, a cancer of the eye that develops mainly in children, inherited a mutation in a gene called RB1 from a parent (9). Inherited mutations associated with certain familial syndromes, such as Li-Fraumeni syndrome, Beckwith-Wiedemann syndrome, Fanconi anemia syndrome, Noonan syndrome, and von Hippel-Lindau syndrome, also increase the risk of childhood cancer.
Genetic mutations that initiate cancer can also arise during the development of a fetus in the womb. Evidence for this comes from studies of monozygotic (identical) twins in which both twins developed leukemia with an identical leukemia-initiating gene mutation (10).
Children who have Down syndrome, a genetic condition caused by the presence of an extra copy of chromosome 21, are 10 to 20 times more likely to develop leukemia than children without Down syndrome (11). However, only a very small proportion of childhood leukemia is linked to Down syndrome.
Most cancers in children, like those in adults, are thought to develop as a result of mutations in genes that lead to uncontrolled cell growth and eventually cancer. In adults, these gene mutations are often the result of exposure to cancer-causing environmental factors, such as cigarette smoke, asbestos, and ultraviolet radiation from the sun. One study found that melanoma in children and adolescents (ages 11–20 years) has many genomic similarities to melanoma that occurs in adults, including an enrichment of UV-induced mutations (12).
However, environmental causes of childhood cancer have been difficult to identify, partly because cancer in children is rare, and partly because it is difficult to determine what children might have been exposed to early in their development. In fact, most childhood cancers are not thought of as being caused by environmental exposures.
Nevertheless, several environmental exposures have been linked to childhood cancer. One is ionizing radiation, which can lead to the development of leukemia and other cancers in children and adolescents. For example, children and adolescents who were exposed to radiation from the atomic bombs dropped in Japan during the Second World War had an elevated risk of leukemia (13), and children who were exposed to radiation from the Chernobyl nuclear plant accident had an elevated risk for thyroid cancer (14). Children whose mothers had x-rays during pregnancy (that is, children who were exposed before birth) and children who were exposed after birth to diagnostic medical radiation from computed tomography (CT) scans have also been found to have an increased risk of leukemia and brain tumors, and possibly other cancers (15).
A number of other environmental exposures have also been reported to have possible associations with childhood cancer. However, because of challenges in studying these associations, such as recall bias and the difficulty of determining exposure at the relevant time period in a child’s development, it is difficult to draw firm conclusions. Some types of childhood leukemia have been associated with father’s tobacco smoking (16, 17); with exposure to certain pesticides used in and around the home (18) or by parents at their workplace (19, 20); with solvents, which are organic chemicals that are found in some household products; and with outdoor air pollution. Studies of childhood brain tumors have suggested possible associations with exposures to pesticides in and around the home (21) and maternal consumption of cured meats (22).
Researchers have also identified factors that may be associated with reduced risk of childhood cancer. For example, maternal consumption of folate has been associated with reduced risks of both leukemia and brain tumors in children (23). And being breastfed and having been exposed to routine childhood infections are both associated with a lowered risk of developing childhood leukemia (24).
What does a child’s cancer diagnosis mean for cancer risk in the rest of the family?
First- and second-degree relatives of a child diagnosed with cancer, particularly if diagnosed before age five, may be at increased risk for developing cancer if there is already a family history of cancer—that is, if the child’s cancer is likely due to an inherited genetic syndrome (25). A clinician may advise as to whether a child could benefit from genetic testing or referral to a medical geneticist for evaluation (25–27).
How do cancers in adolescents and young adults differ from those in younger children?
Cancer occurs more frequently in adolescents and young adults ages 15 to 39 years than in younger children, although incidence in this group is still much lower than in older adults. According to the NCI Surveillance, Epidemiology, and End Results (SEER) program (7), each year in 2011–2015 there were:
- 16 cancer diagnoses per 100,000 children ages 0 to 14 years
- 72 cancer diagnoses per 100,000 adolescents and young adults ages 15 to 39 years
- 953 cancer diagnoses per 100,000 adults aged 40 years or older
The most frequent cancers diagnosed in adolescents and young adults (AYAs) are cancers that are more common among adults than younger children, such as breast cancer, melanoma, and thyroid cancer (28). But certain cancers, such as testicular cancer, are more typical of AYAs than of either younger children or adults (7). However, the incidence of specific cancer types varies widely across the adolescent and young adult age continuum.
Where do children with cancer get treated?
Children who have cancer are often treated at a children’s cancer center, which is a hospital or a unit within a hospital that specializes in diagnosing and treating children and adolescents who have cancer. Most children’s cancer centers treat patients through 20 years of age. The health professionals at these centers have specific training and expertise to provide comprehensive care for children, adolescents, and their families.
Recently, many Adolescent and Young Adult (AYA) cancer programs have been created to address the unique needs of teens and young adults. Areas of focus include long-term survivor care, access to clinical trial enrollment, discussing and preserving future fertility, peer support, and psychosocial support that addresses their personal issues, including finances, education, occupational impacts, and transition to independence.
Children’s cancer centers also participate in clinical trials. The improvements in survival for children with cancer that have occurred over the past half century have been achieved because of treatment advances that were studied and proven to be effective in clinical trials.
More than 90% of children and adolescents who are diagnosed with cancer each year in the United States are cared for at a children’s cancer center that is affiliated with the NCI-supported Children’s Oncology Group Exit Disclaimer (COG). COG is the world’s largest organization that performs clinical research to improve the care and treatment of children and adolescents with cancer. Each year, approximately 4,000 children who are diagnosed with cancer enroll in a COG-sponsored clinical trial. COG trials are sometimes open to individuals aged 29 years or even older when the type of cancer being studied is one that occurs in children, adolescents, and young adults.
Every children’s cancer center that participates in COG has met strict standards of excellence for childhood cancer care. A directory of COG locations Exit Disclaimer is available on their website. Families can ask their pediatrician or family doctor for a referral to a children’s cancer center. Families and health professionals can call NCI’s Cancer Information Service at 1–800–4–CANCER (1–800–422–6237) to learn more about children’s cancer centers that belong to COG.
If my child is treated at a children’s cancer center, will he or she automatically be part of a clinical trial?
No. Participation in a clinical trial is voluntary, and it is up to each family to decide if clinical trial participation is right for their child.
Can children who have cancer be treated at the National Institutes of Health (NIH) Clinical Center?
Children with cancer may be eligible to be treated in clinical trials at the NIH Clinical Center in Bethesda, Maryland. Because the NIH Clinical Center is a research hospital, only patients who have a specific type or stage of cancer that is under study can be accepted for treatment. In some cases, patients with conditions that are rare or difficult to diagnose may also be accepted for treatment at the Clinical Center. All patients who are treated at the Clinical Center must be referred by a physician.
NCI’s Pediatric Oncology Branch conducts clinical trials for children, adolescents, and young adults with a wide variety of cancers. Patients with newly diagnosed cancer, as well as patients whose cancers have come back after treatment, may be eligible to participate in a clinical trial. Physicians at the Pediatric Oncology Branch can also provide a second opinion on a patient’s diagnosis or treatment plan. To refer a patient to the Pediatric Oncology Branch, the patient’s health care provider should call 301–496–4256 (local) or 1–877–624–4878 (toll-free) weekdays between 8:30 a.m. and 5:00 p.m. ET. Parents can also call these numbers to learn if their child is eligible to participate in a clinical trial.
What should survivors of childhood cancer consider after they complete treatment?
Survivors of childhood cancer need follow-up care and enhanced medical surveillance for the rest of their lives because of the risk of complications related to the disease or its treatment that can last for, or arise, many years after they complete treatment for their cancer. Health problems that develop months or years after treatment has ended are known as late effects.
The specific late effects that a person who was treated for childhood cancer might experience depend on the type and location of his or her cancer, the type of treatment he or she received, and patient-related factors, such as age at diagnosis.
Children who were treated for bone cancer, brain tumors, and Hodgkin lymphoma, or who received radiation to their chest, abdomen, or pelvis, have the highest risk of serious late effects from their cancer treatment, including second cancers, joint replacement, hearing loss, and congestive heart failure (29, 30).
Long-term follow-up analysis of a cohort of survivors of childhood cancer treated between 1970 and 1986 has shown that cancer survivors remain at risk of complications and premature death as they age, with more than half of survivors having experienced a severe or disabling complication or even death by the time they reach age 50 years (31). Children treated in more recent decades may have lower risks of late effects due to modifications in treatment regimens to reduce exposure to radiotherapy and chemotherapy, increased efforts to detect late effects, and improvements in medical care for late effects (32).
It’s important for childhood cancer survivors to have regular medical follow-up examinations so any health problems that occur can be identified and treated as soon as possible. The Children’s Oncology Group (COG) has developed long-term follow-up guidelines Exit Disclaimer for survivors of childhood, adolescent, and young adult cancers.
It is also important to keep a record of the cancer treatment that a child received. This record should include:
- The type and stage of cancer
- Date of diagnosis and dates of any relapses
- Types and dates of imaging tests
- Contact information for the hospitals and doctors who provided treatment
- Names and total doses of all chemotherapy drugs used in treatment
- The parts of the body that were treated with radiation and the total doses of radiation that were given
- Types and dates of all surgeries
- Any other cancer treatments received
- Any serious complications that occurred during treatment and how those complications were treated
- The date that cancer treatment was completed
The record should be kept in a safe place, and copies of the record should be given to all doctors or other health care providers who are involved with the child’s follow-up care, even as the child grows into adulthood.
Many children’s cancer centers have clinics where survivors of childhood cancer can go for follow-up until they reach their early 20s. Some cancer centers are now creating clinics dedicated to follow-up care for long-term survivors of pediatric and adolescent cancers.