According to the National Cancer Institute (NCI), brain tumors are the most common solid tumor in children. Brain tumors in children can be benign (not cancer) or malignant (cancer is present). The most common malignant brain tumors in children are gliomas, ependymomas, and medulloblastomas. The names of brain tumors come from the site of development, but approximately half of all brain tumors in children are gliomas. Gliomas develop from the cells that surround and support nerve cells (glial cells). There are no known causes of brain cancer in children, according to the American Cancer Society (ACS), but there are factors that are being investigated by scientists.
Gene Mutations
Brain tumors are caused by cells reproducing themselves in an uncontrolled manner. Cells contain a chemical known as DNA, which is made up of genes that provide a road map for how the cell should function. Children inherit genes from both parents. When cells divide too rapidly (oncogenes), or when tumor suppressor genes do not slow abnormal cell division, cancer may develop. Gene changes can be inherited from parents in some childhood cancers, or the gene may mutate (change) for no known reason after birth. For example, if the suppressor gene called p53 mutates, it increases the risk of developing some cancers, including brain cancer.
Inherited Risk Factors
The ACS reports that some rare inherited syndromes can increase the risk of some central nervous system tumors (the brain is part of the central nervous system). Children, in rare cases, can inherit an abnormal gene from one or both parents. Children with neurofibromatosis type 1, also known as von Recklinghausen disease, may have gliomas on the optic nerve (the nerve of the eye), or in the brain due to a problem with the NF1 gene. This is the most common inherited cause of brain tumors. Cranial (head) nerve tumors or acoustic neuromas (tumor on the nerve related to hearing) are seen in neurofibromatosis type 2 with changes in the NF2 gene. Changes in the VHL gene cause Von Hippel-Landau disease. Children with this gene change may develop blood vessel tumors in the brain, retina of the eye or spinal cord. Other inherited disorders including retinoblastoma also may increase the risk of brain tumors.
Environmental Factors
The only direct, proven environmental link to brain cancer in children is radiation to the head. Exposure to things in the environment is a suspected cause of brain cancer in children. Scientists at the National Cancer Institute continue to investigate whether exposure to substances before and during pregnancy and after birth could be a causative factor. Since each type of childhood cancer develops differently and the number of brain tumors in children is relatively small, determining a direct link between exposure to substances in the environment and brain cancer is extremely difficult. Any chemical, such as pesticides, artificial sweeteners, colorings in food, and cleaning agents, could be determined to cause problems in future studies, so children should be protected as much as possible from unnecessary exposure.
