Astrocytomas
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 brain tumors. Most cases occur between the ages of 5 years and 9 years. These tumors can occur anywhere in the brain or spinal cord but are most common in the cerebellum.
Symptoms and Signs
Diagnosis
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) or high grade (eg, glioblastoma—see Table: World Health Organization (WHO) Grading of Select Astrocytic Tumors). Many pathologists designate grades I and II tumors as low grade and grades III and IV tumors as high grade. However, because grade II tumors have a higher risk of relapse, some pathologists think these tumors should not be considered low grade.
World Health Organization (WHO) Grading of Select Astrocytic Tumors
|
Tumor |
Tumor Grade |
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|
|
I |
II |
III |
IV |
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Subependymal giant cell astrocytoma |
X |
|
|
|
|
Pilocytic astrocytoma |
X |
|
|
|
|
Diffuse astrocytoma (IDH-mutant) |
|
X |
|
|
|
Pleomorphic xanthoastrocytoma |
|
X |
|
|
|
Oligodendroglioma (IDH-mutant and 1p/19q-codeleted) |
|
X |
|
|
|
Anaplastic astrocytoma (IDH-mutant) |
|
|
X |
|
|
Anaplastic pleomorphic xanthoastrocytoma |
|
|
X |
|
|
Anaplastic oligodendroglioma (IDH-mutant and 1p/19q-codeleted) |
|
|
X |
|
|
Diffuse midline glioma (H3K27M-mutant) |
|
|
|
X |
|
Glioblastoma (IDH-wildtype, or IDH-mutant) |
|
|
|
X |
|
Adapted from Louis DN, Perry A, Reifenberger G, et al: The 2016 World Health Organization classification of tumors of the central nervous system: A summary. Acta Neuropathologica 131(6): 803–820, 2016. |
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Treatment
Treatment of astrocytoma 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.
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Low grade: Surgical resection is the primary treatment, and total resection is the goal. Even after local recurrence, a second surgical resection can be beneficial depending on the location of the tumor. Radiation therapy is usually reserved for children who are > 10 years old and whose tumors are unresectable, cannot be completely excised, or progress/recur after surgery. For children < 10 years old whose tumors are unresectable or progress/recur after surgery, chemotherapy is used instead because radiation therapy may cause long-term cognitive impairment. Most children with low-grade astrocytomas are cured.
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High grade: These tumors are treated with a combination of surgery (unless location precludes it), radiation therapy, and chemotherapy. Prognosis is poor; overall survival at 3 years is only 20 to 30%.
