What is Childhood Cancer?
About 10,400 children under the age of 15 in the United States will be diagnosed with cancer in 2007. Because of significant advances in therapy, 79% of these children will survive 5 years or more. This is a major increase from before the 1970s, when the 5-year survival rate was less than 50%.
Despite its rarity and the impressive strides in treatment and supportive care, cancer is still the leading cause of death (an estimated 1,545 deaths in 2007) from disease in children younger than 15 years old, second only to accidents in most age groups.
The types of cancers that occur in children vary greatly from those seen in adults. Leukemias, brain and other nervous system tumors, lymphomas (lymph node cancers), bone cancers, soft tissue sarcomas, kidney cancers, eye cancers, and adrenal gland cancers are the most common cancers of children, while skin, prostate, breast, lung, and colorectal cancers are the most common in adults. The stage of growth and development is another important difference between adults and children. The immaturity of children's organ systems often has important effects on treatment.What are the Risk Factors and Causes of Childhood Cancer?
A risk factor is anything that is linked to an increased chance of getting a disease such as cancer. Lifestyle-related risks are the main factors that contribute to cancers in adults. Examples include the effect of unhealthy diets (low consumption of fruits and vegetables, etc.), not enough exercise, and habits such as smoking and drinking alcohol. Lifestyle-related risk factors have little or no significance in childhood cancer.
Cancer is caused by a mutation (change) in a gene. During the past few years, scientists have made great progress in understanding how certain changes in a person's DNA can cause cells of the body to become cancerous. DNA carries the instructions for nearly everything our cells do. We usually resemble our parents because they are the source of our DNA. However, DNA affects more than our outward appearance. It influences our risks for developing certain diseases, including some kinds of cancer. When children are born with mutated DNA that was inherited from parents, the mutations are present in every cell of the child's body. That means the mutations can be detected by testing DNA of blood cells.
The great majority of cancers, however, are not caused by inherited DNA mutations. They are the result of mutations acquired early in the child's lifetime. Every time a cell prepares to divide into 2 new cells, it must copy its DNA. This process is not perfect, and errors sometimes occur. Luckily, cells have repair enzymes that "proofread" DNA. Some errors can still slip past, especially when the cells are growing rapidly. This kind of gene mutation can happen at any time in life. Acquired mutations start in one cell of the body, and that cell passes the mutation on to all the cells that spring from it. These acquired mutations are present only in the patient's cancer cells and will not be passed on to his or her children. Although the causes of mutations responsible for certain adult cancers are known (for example, cancer-causing chemicals in cigarette smoke), the reasons for DNA changes that cause childhood cancers are not known. Some of these can occur in developing fetuses and are already present at birth.
Can Childhood Cancer Be Found Early?
Cancers in children often are difficult to recognize. Parents should see that their children have regular medical checkups and watch for any unusual signs or symptoms that persist. These include an unusual mass or swelling; unexplained paleness and loss of energy; sudden tendency to bruise; a persistent pain in one area of the body; limping; prolonged, unexplained fever or illness; frequent headaches, often with vomiting; sudden eye or vision changes; and excessive, rapid weight loss.
Although many adult cancers can be prevented by lifestyle changes that reduce certain risk factors, there is currently no known way to prevent most childhood cancers.
Children who are known to have a higher chance of developing cancer due to known genetic risks should receive careful periodic medical checkups.
How are Childhood Cancers Treated?
Childhood cancers can be treated with a combination of treatments (chemotherapy, surgery, radiation therapy) that are chosen based on the type and stage of cancer. Although there are exceptions, childhood cancers tend to respond well to chemotherapy because they are cancers that grow fast. Most forms of chemotherapy affect only cells that are growing.
Children with cancer and their families have special needs that can be best met by children's cancer centers. Treatment of childhood cancer in specialized centers is coordinated by a team of experts who know the differences between adult and childhood cancers, as well as the unique needs of children with cancers. This team usually includes pediatric oncologists, surgeons, radiation oncologists, pediatric oncology nurses and nurse practitioners.
The treatment of childhood cancer also involves many professionals other than nurses and doctors. Children's cancer centers have psychologists, social workers, child life specialists, nutritionists, rehabilitation and physical therapists, and educators who can support and educate the entire family.
Since the 1960s, most children with cancer have been treated at specialized centers designed for children. About 94% of children with cancer in the United States are treated at a children's cancer center that is a member of the Children's Oncology Group (COG). All of these centers are associated with a university and most with a children's hospital.
These centers will be able to offer your child the most up-to-date-treatment through participation clinical trials, or studies of promising new therapies. Because childhood cancers are uncommon, treatment outcomes are more successful when the treatment is managed by a cancer center. Be sure your child is treated at a center that can offer him or her the option of a clinical trial.
Five-year survival rates vary considerably, depending on the type of cancer your child has. Overall, 5-year relative survival rates have improved greatly over the past 30 years, from less than 50% before the 1970s to nearly 80% today, due to new and improved treatments. The 5-year survival rate for neuroblastoma is 69%; brain and other nervous system, 74%; bone and joint, 72%; leukemia, 81%; Wilms tumor (kidney), 92%; and Hodgkin lymphoma, 95%, and non-Hodgkin lymphoma, 86%.
The 5-year survival rate refers to the percentage of patients who live at least 5 years after their cancer is diagnosed. Five-year rates are used to produce a standard way of discussing prognosis (outlook for recovery and survival). Of course, many children live much longer than 5 years. Five-year survival rates are based on patients who were diagnosed and treated more than 5 years ago. Improvements in treatment often result in a better outlook for recently diagnosed patients.
Survivors of childhood cancer may experience treatment-related side effects months or years after their childhood cancer. These effects can include organ malfunction, second cancers, and problems with mental tasks. The Children's Oncology Group (COG) has recently developed long-term follow-up guidelines for screening and management of late effects in survivors of childhood cancer. For more information on follow up after treatment of childhood cancer, see their Web site at www.survivorshipguidelines.org.
