About Childhood Cancers
What should people know about childhood cancers?
In New York State, about 900 children under the age of 20 are diagnosed with cancer each year. Childhood cancer is the second leading cause of death among children, after injuries. Despite these statistics, childhood cancers are rare, making up fewer than 1 percent of all cancers. Because of significant advances in diagnosis and treatment, over 80 percent of children diagnosed with cancer will survive for five years or more, compared with about 60 percent in the mid-1970s.
What are the most common types of childhood cancer?
The most common types of cancer in children are leukemia, cancers of the brain and nervous system, and lymphoma (including both Hodgkin and non-Hodgkin lymphoma).
Leukemia is cancer of the blood cells. Leukemia occurs when the bone marrow makes abnormal blood cells, usually white blood cells, that do not function as they should. The most common type of leukemia in children is acute lymphocytic leukemia (ALL). ALL is a cancer of the lymphocyte type of white blood cell that progresses rapidly. Over the past 50 years, there has been dramatic improvement in survival rates for children with ALL. In 1960, only 4 percent of children with ALL lived five or more years. Now, the five-year survival rate for children with ALL is over 85 percent.
Tumors of the brain, spinal cord and other parts of the nervous system are the most common types of solid tumors in children. These tumors can be malignant (cancerous) or benign (non-cancerous). Because of their location, tumors of the brain and other parts of the nervous system can be difficult to diagnose and treat.
Lymphoma is cancer that starts in lymphocytes, infection-fighting cells that are a part of the body's immune system. Lymphocytes may be found in lymph nodes (small, oval-shaped organs located throughout the body) and in many organs. There are two main types of lymphoma - Hodgkin lymphoma (formerly called Hodgkin's disease) and non-Hodgkin lymphoma. Hodgkin lymphoma is rare in young children, but is the type of lymphoma most frequently seen in teenagers. Non-Hodgkin lymphoma occurs more often than Hodgkin lymphoma among younger children, but less often than Hodgkin lymphoma in teenagers.
Other cancers that occur in children include bone cancer, soft-tissue cancers, neuroblastoma, retinoblastoma, and kidney cancer. Bone cancer, including osteogenic sarcoma and Ewing sarcoma, occurs most often during teenage growth spurts. Soft tissue cancers include cancers of the muscles, fat, blood vessels, nerves, tendons, and tissues that surround the bones and joints. The most common soft tissue cancer in children is rhabdomyosarcoma, which arises in the muscles. Neuroblastoma is cancer of the sympathetic nervous system, a part of the nervous system that unconsciously controls the body's responses such as heart beat. Neuroblastoma is found only in children, most often before the age of five. It is most frequently found in the adrenal glands and in the chest and abdomen. Retinoblastoma is a malignant tumor of the eye that occurs in young children generally before the age of five. Wilms tumor is the most common type of cancer of the kidney in children. It usually occurs between the ages of two and four years, and is rare in children over the age of seven.
What factors increase a child's risk of developing cancer?
At this time, the causes of childhood cancers are not well understood. However, certain factors have been identified that increase a child's risk of developing some types of cancer. These risk factors include:
- Genetics and hereditary conditions. Certain genetic conditions and diseases that run in families have been linked with specific types of cancer in children. Neurofibromatosis (von Recklinghausen's disease) and the rare Li-Fraumeni cancer family syndrome have each been linked with several different childhood cancers. Children with Down syndrome are at increased risk of leukemia. The retinoblastoma gene, besides being linked with almost half of all cases of retinoblastoma, also has been linked with some cases of osteosarcoma. People with a family history of Hodgkin lymphoma or neuroblastoma are at a higher risk of these cancers.
- Ionizing radiation. Prenatal exposure to diagnostic X-rays has been associated with the development of childhood leukemia. Exposure to high doses of ionizing radiation for the treatment of other conditions has been linked with brain tumors and bone cancer. In the past, ionizing radiation was used for medical purposes more than it is today. With the reduction in medical uses, the importance of ionizing radiation as a cause of childhood cancers also has declined.
- Infections. Hodgkin lymphoma in teenagers has been associated with the Epstein-Barr virus, the virus that causes mononucleosis. However, most people who have had mononucleosis do not develop Hodgkin lymphoma. As with adults, children with AIDS or the virus that causes it (HIV) are more likely to develop non-Hodgkin lymphoma.
These known risk factors together, however, only account for a small fraction of cancers in children.
What other risk factors for childhood cancers are scientists studying?
Scientists are studying a variety of factors that may influence the risk of a child developing different types of cancer. These include exposures the child's parents may have had before the child was conceived, such as exposures in the workplace. Scientists are also interested in prenatal exposures to the child, and conditions at the time of birth, including having a high birth weight (3500 grams/7.7 pounds or more), a very low birth weight (1500 grams/3.3 pounds or less), or a mother who was older (over age 35).
Researchers are also looking into the possible roles of childhood dietary factors, certain viruses, childhood infections in general, and exposure to various chemicals, such as pesticides. Some studies have suggested that being breastfed may decrease the risk of several types of cancer.
More research is needed to determine the role, if any, that these factors may have in the development of childhood cancers.
What are the symptoms of childhood cancer?
Cancer in children is difficult to recognize. Parents can help ensure that childhood cancers are recognized and treated promptly by having their children see a health care provider regularly and being aware of any unusual, persistent symptoms or problems. Possible symptoms of childhood cancers include:
- an unusual mass or swelling,
- paleness and loss of energy,
- bruising easily,
- persistent pain or limping,
- unexplained fever,
- frequent headaches, especially if accompanied by vomiting,
- eye or vision changes,
- rapid weight loss.
Although any of these may be caused by other conditions or illnesses, symptoms such as these should be brought to the attention of the child's health care provider.
What else can parents do?
Parents can lay a good foundation for the prevention of cancer and other chronic diseases later on in life by seeing to it that their children follow good health practices (and following these practices themselves). Good health practices include:
- Eating a healthy diet to achieve and maintain a healthy weight. This includes eating plenty of vegetables, fruits and whole grains and less red and processed meats (e.g., bacon, sausage, luncheon meats, hot dogs). These actions may reduce the risk of developing many types of cancer as well as other diseases.
- Exercising regularly.
- Finding out about the benefits and risks of diagnostic scanning to avoid unnecessary exposure to ionizing radiation. This is especially important for children and pregnant women.
- Not smoking, and avoiding exposures to second hand smoke. People who currently smoke should quit. For more information on quitting smoking, visit the NYS Smoker's Quitline at www.nyssmokefree.com or call 1-866-NY-QUITS.
What is being done to fight childhood cancers?
Research is going on at institutions throughout New York State and the nation to further the gains made in treating childhood cancers. Most children with cancer are now seen at specialized cancer treatment centers. At these centers, most patients are offered the chance to take part in clinical trials to test out promising new treatments. The federally supported Children's Oncology Group offers clinical trials for most types of childhood cancer at 14 childhood cancer treatment centers across New York.
For more information:
- National Cancer Institute
- American Cancer Society
- Centers for Disease Control and Prevention
- American Society of Clinical Oncology
- Children's Oncology Group