Overview: Pediatric Tumor Types
Brain tumors are the second most common type of cancer in children and the single most common type of solid cancer in children. They account for 21% of all childhood cancer. About 3200 children in the United States are diagnosed with new non-malignant and malignant brain and spinal cord tumors each year. Pediatric brain tumors are identified the same way as their adult counterparts, using the World Health Organization classification system. There are over 120 types of brain tumors, and occasionally the same tumor may even be called by different names. The most important things to know are where the tumor is located (how close it is to areas of critical brain functions), how fast it is expected to grow, and how susceptible it may be to different kinds of treatments. Almost all pediatric brain tumors are primary tumors, meaning the brain is the first site where they appear. Children’s tumors behave differently than those in adults. Because the brain in a child is still growing and forming connections, it is more vulnerable than the adult brain. It is especially important for children to be treated at a center with experience in pediatric brain tumors and has a wide array of specialists to provide all aspects of care.
Astrocytomas are tumors that arise from astrocytes, the supporting cells in the brain. These cells are also called glial cells, and thus astrocytomas are also called gliomas. Astrocytomas are the most common pediatric brain tumors. They are graded I-IV, with I being the lowest grade and IV being the highest. As in adults, grade I and II astrocytomas are called low-grade and grades III and IV are called high grade. However, unlike astrocytomas in adults, low grade pediatric astrocytomas are not known to progress to high grade astrocytomas. A pediatric grade II astrocytoma is highly unlikely to become a grade III, no matter how long the patient has the tumor.
Low Grade Gliomas
Gliomas arise from the supportive glial cells within the brain. Low-grade gliomas (astrocytomas) can occur throughout the brain and spine. Complete surgical resection, when feasible, is the primary treatment for low-grade gliomas. If the tumor is completely removed, often no additional therapy is required. However, there are a number of low-grade tumors that cannot be completely removed or resected at all, such as tumors of the optic pathway, thalamus, or brainstem. Tumors in these locations can usually be effectively treated with chemotherapy and/or radiation therapy. Historically, radiation therapy was the primary treatment for these tumors. In the last decade, in an attempt to minimize treatment related late-effects, chemotherapy regimens have replaced radiation as the initial treatment.
High Grade Gliomas
High-grade gliomas (astrocytomas) also occur in childhood. For the most part these tumors behave very much like adult high-grade gliomas. The most common high-grade tumor seen in the pediatric population are the diffuse pontine gliomas. These are high-grade astrocytomas that occur within the brainstem and are considered inoperable. Radiation and experimental chemotherapy are the primary treatments used for diffuse pontine gliomas to prolong life, but unfortunately cure is not usually possible for these tumors.
Ependymomas, another subtype of gliomas, comprise 5-10% of pediatric CNS tumors. They arise from the ependymal cells that line the ventricular system in the brain or central canal of the spinal cord. Within the brain, the most common site of occurrence is in the posterior fossa, or 4th ventricle. Ependymomas usually occur in very young children, with half of new cases developing in children younger than 5 years of age. The extent of tumor resection is the single most important prognostic factor for long-term survival. Ependymomas that occur in the spine or supratentorial areas of the brain and can be completely removed typically do not need additional treatment. Incompletely resected ependymomas or completely resected tumors located in the posterior fossa are usually treated with radiation, when feasible. Chemotherapy has historically not been considered very effective for improving survival for patients with ependymomas. Now, however, a number of neuro-oncologists are challenging this assumption and use chemotherapy in relapsed patients or those too young to receive radiation.
Medulloblastomas are the second most common brain tumor in children. Medulloblastomas arise from the cerebellum, the back part of the brain, and originate from immature neuronal cells. While most occur locally in the cerebellum, medulloblastoma can spread within the brain and spine, and on rare occasion outside of the brain into bone marrow. Treatment for medulloblastoma involves attempting to totally remove the tumor by surgery, treating the entire spine and brain with radiation, and a year of multi-agent chemotherapy. The overall prognosis for a newly diagnosed patient is good if the patient is older than 3 years of age, has focal tumor only (one site), and the neurosurgeon is able to totally or near totally remove the tumor. Children who meet these criteria are said to have “standard-risk” medulloblastoma. Children who are less than 3 years of age, or those with multi-focal disease or have a large amount of tumor left behind from surgery are considered to be “high-risk” and usually require more intensive treatment. Advances in treatment of pediatric brain tumors have led to increased survival. Despite these continued improvements, many young survivors still face physical, psychological, intellectual and social challenges directly related to their treatment. It is important that these survivors receive ongoing assessment and specialized care to best support their functioning at school and throughout life.
Treatments for children with brain tumors is available locally at NeuroSpine Center of Wisconsin. From surgery to radiation, the most advanced treatments are provided by our expert neurosurgical staff. In addition, support services for the children and their families is offered though the Fox Valley Brain Tumor Coalition, with financial assistance and the largest support group in the Midwest.
For more information call 920-882-8200 or 1-888-231-5236