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 2014, it is estimated that 15,780 children and adolescents ages 0 to 19 years will be diagnosed with cancer and 1,960 will die of the disease in the United States (1).
The most common types of cancer diagnosed in children and adolescents are leukemia, brain and other central nervous system tumors, lymphoma, rhabdomyosarcoma, neuroblastoma, Wilms tumor, bone cancer, and gonadal (testicular and ovarian) germ cell tumors.
As of January 1, 2010, there were approximately 380,000 survivors of childhood and adolescent cancer (diagnosed at ages 0 to 19 years) alive in the United States (1). 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 with cancer?
The overall outlook for children with cancer has improved greatly over the last half-century. In 1975, just over 50 percent of children diagnosed with cancer before age 20 years survived at least 5 years (2). In 2004-2010, more than 80 percent of children diagnosed with cancer before age 20 years survived at least 5 years (3).
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 1970s raised the 5-year survival rate for childhood acute lymphoblastic leukemia from less than 10 percent in the 1960s to about 90 percent in 2003-2009. Survival rates for childhood non-Hodgkin lymphoma have also increased dramatically, from less than 50 percent in the late 1970s to 85 percent in 2003-2009.
By contrast, survival rates remain very low for some cancer types, for some age groups, and for some cancers within a site. For example, median survival for children with diffuse intrinsic pontine glioma (a type of brain tumor) is less than 1 year from diagnosis (4). Among children with Wilms tumor (a type of kidney cancer), older children (those diagnosed between ages 10 and 16 years) have worse 5-year survival rates than younger children (5). For soft tissue sarcomas, 5-year survival rates among children and adolescents ages 0 to 19 years range from 64 percent (rhabdomyosarcoma) to 72 percent (Ewing sarcoma) (1). And 5-year survival rates for central nervous system cancers range from 70 percent (medulloblastoma) to 85 percent (astrocytoma) (1).
The cancer mortality rate—the number of deaths due to cancer per 100,000 people per year—among children ages 0 to 19 years declined by more than 50 percent from 1975-1977 to 2007-2010 (6). More specifically, the mortality rate was slightly more than 5 per 100,000 children in 1975 and about 2.3 per 100,000 children in 2010. However, despite the overall decrease in mortality, nearly 2,000 children 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.
What are the possible causes of cancer in children?
The causes of most childhood cancers are not known. About 5 percent of all cancers in children are caused by an inherited mutation (a genetic mutation that can be passed from parents to their children). For example, 25 to 30 percent of cases of retinoblastoma, a cancer of the eye that develops mainly in children, are caused by an inherited mutation in a gene called RB1 (7). However, retinoblastoma accounts for only about 3 percent of all cancers in children. 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 cause cancer can also arise during the development of a fetus in the womb. For example, one in every 100 children is born with a genetic abnormality that increases risk for leukemia, although only one child in 8,000 with that abnormality actually develops leukemia (8).
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 (9). 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 environmental factors, such as cigarette smoke, asbestos, and ultraviolet radiation from the sun. 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.
Many studies have shown that exposure to ionizing radiation can damage DNA, which can lead to the development of childhood leukemia and possibly other cancers. For example, children and adolescents who were exposed to radiation from the World War II atomic bomb blasts had an elevated risk of leukemia (10), and children and adults who were exposed to radiation from accidents at nuclear power plants had an elevated risk for thyroid cancer (11). 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 scans also have an increased risk of some cancers (12).
Studies of other possible environmental risk factors, including parental exposure to cancer-causing chemicals, prenatal exposure to pesticides, childhood exposure to common infectious agents, and living near a nuclear power plant, have so far produced mixed results. Whereas some studies have found associations between these factors and risk of some cancers in children, other studies have found no such associations (8,13-15). Higher risks of cancer have not been seen in children of patients treated for sporadic cancer (cancer not caused by an inherited mutation) (16).
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. About 70,000 adolescents and young adults ages 15 to 39 years are diagnosed with cancer in the United States each year.
Adolescents and young adults are often diagnosed with different types of cancer than either younger children or older adults. For example, adolescents and young adults are more likely than either younger children or older adults to be diagnosed with Hodgkin lymphoma, melanoma, testicular cancer, thyroid cancer, and sarcoma (17). However, the incidence of specific cancer types varies widely across the adolescent and young adult age continuum.
The 5-year overall survival rate among adolescents ages 15 to 19 years with cancer exceeded 80 percent in 2003-2007, similar to that among younger children (6). However, for specific diagnoses, survival is lower for 15- to 19-year-olds than for younger children. For example, the 5-year survival rate for acute lymphoblastic leukemia in 2003-2007 was 91 percent for children younger than 15 years compared with 78 percent for adolescents ages 15 to 19 years (6).
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 (18). The improvement in 5-year survival rates for 15- to 19-year-olds with acute lymphoblastic leukemia—from approximately 50 percent in the early 1990s to 78 percent in 2003-2007—may reflect greater use of these pediatric treatment regimens (6). In 2000-2010, mortality rates for 15- to 19-year-olds declined at a slightly faster rate than those for younger children (by 2.6 percent per year versus 1.8 percent per year) (6).
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 up to 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.
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 percent 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 (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.
Every children’s cancer center that participates in COG has met strict standards of excellence for childhood cancer care. A directory of COG locations is available on COG’s 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 (CIS) at 1–800–4–CANCER 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 that can occur 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. Indeed, 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 (19). It is not known whether children treated in more recent periods will experience similar risks of late complications.
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 (20,21).
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 has developed long-term follow-up guidelines for survivors of childhood, adolescent, and young adult cancer.
It is also important to keep a record of the cancer treatment that someone received as a child. 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
Several cancer support organizations have developed kits that can help parents keep track of this information. The NCI booklet Facing Forward: Life After Cancer Treatment includes a list of these organizations in the section "Guidelines for Follow-up Care." 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 follow-up 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 cancer survivors.