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Brain Tumors in Children
Brain tumors are the most common solid cancer in children < 15 yr and are the 2nd leading cause of death due to cancer. Diagnosis is typically by imaging (usually MRI) and biopsy. Treatment may include surgical resection, chemotherapy, and radiation therapy.
Entry into a clinical trial should be considered for all children with a brain tumor. Optimal treatment requires a multidisciplinary team of oncologists who have experience treating brain tumors in children. Because radiation therapy for brain tumors is technically demanding, children should be sent to centers that have experience in this area if possible.
Astrocytomas range from low-grade indolent tumors (the most prevalent) to malignant high-grade tumors. As a group, astrocytomas are the most common brain tumor in children, representing about 40% of tumors. Most cases occur between ages 5 yr and 9 yr. These tumors can occur anywhere in the brain or spinal cord, but are most common in the cerebellum.
Most patients have symptoms consistent with increased intracranial pressure (eg, morning headaches, vomiting, lethargy). Location of the tumor determines other symptoms and signs; for example:
Contrast-enhanced MRI is the imaging test of choice for diagnosing the tumor, determining extent of disease, and detecting recurrence. Contrast-enhanced CT can also be used, although it is less specific and less sensitive. Biopsy is needed for determining tumor type and grade. These tumors are typically classified as low-grade (eg, juvenile pilocytic astrocytoma), intermediate-grade, or high-grade (eg, glioblastoma).
Treatment depends on location and grade of tumor. As a general rule, the lower the grade of the tumor, the less intensive the therapy and the better the outcome.
Low-grade: Surgical resection is the primary treatment. Radiation therapy is reserved for children who are > 10 yr and whose tumors cannot be completely excised. For children < 10 yr with incompletely excised tumors, chemotherapy is used instead because radiation therapy may cause long-term cognitive impairment. Most children with low-grade astrocytomas are cured.
Intermediate-grade: These tumors are somewhere between low-grade and high-grade lesions. If they are closer to high-grade tumors, they are treated more aggressively (radiation and chemotherapy); if they appear more like low-grade tumors, they are treated with surgery alone or surgery followed by radiation (older children) or chemotherapy (younger children).
High-grade: These tumors are treated with a combination of surgery (unless location precludes it), radiation therapy, and chemotherapy. Prognosis is poor; overall survival is only 20-30%.
Ependymomas are the 3rd most common CNS tumor in children (after astrocytomas and medulloblastomas), representing 10% of pediatric brain tumors. Mean age at diagnosis is 6 yr; however, about 30% of ependymomas occur in children < 3 yr.
Ependymomas are derived from the ependymal lining of the ventricular system. Up to 70% of ependymomas occur in the posterior fossa; both high-grade and low-grade tumors in the posterior fossae tend to spread locally to the brain stem.
Initial symptoms are typically related to increased intracranial pressure. Infants may present with developmental delay and irritability. Changes in mood, personality, or concentration may occur. Seizures, balance and gait disturbances, or symptoms of spinal cord compression (eg, back pain, loss of bladder and bowel control) may occur.
Diagnosis is based on MRI and biopsy.
The tumor is surgically removed, followed by MRI to check for residual tumor. Radiation therapy, chemotherapy, or both are then required.
Overall 5-yr survival rate is about 50% but depends partly on age:
Survival rate also depends on how much of the tumor can be removed (51 to 80% with total or near-total removal vs 0 to 26% with < 90% removal). Children who survive are at risk of neurologic deficits.
Medulloblastoma is the most common malignant posterior fossa tumor in children and represents about 20% of all pediatric CNS cancers. It most commonly occurs in children aged 5 to 7 yr but can occur throughout adolescence. It is more common among boys. Medulloblastoma is a type of primitive neuroectodermal tumor (PNET).
Etiology is unclear, but medulloblastoma may occur with certain syndromes (eg, Gorlin syndrome, Turcot syndrome).
Patients present most commonly with vomiting, headache, nausea, visual changes (eg, double vision), and unsteady walking or clumsiness.
MRI with gadolinium contrast is the imaging test of choice for initial detection. Biopsy confirms diagnosis. Once the diagnosis is established, MRI of the entire spine along with lumbar puncture and sampling of the CSF are done to assess for spread of tumor into the spinal canal.
Treatment includes surgery, radiation, and chemotherapy. Children under the age of 3 may be effectively treated with chemotherapy alone. Combination therapy typically provides the best long-term survival.
Prognosis depends on the extent, histology, and biologic (eg, histologic, cytogenetic, molecular) parameters of the tumor and patient age:
> 3 yr: Likelihood of 5-yr disease-free survival is 50 to 60% if the tumor is high-risk (disseminated) and 80% if the tumor is average-risk (no dissemination).
≤ 3 yr: Prognosis is more problematic, in part because up to 40% have disseminated disease at diagnosis. Children who survive are at risk of severe long-term neurocognitive deficits (eg, in memory, verbal learning, and executive function).
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