Low+Grade+Astrocytoma

Low Grade Astrocytomas are rare tumors. Only 1500 new cases occur each year. 1 These tumors are classified as Grade II. They are characterized as slow growing tumors and their borders are not well defined. 1 Low Grade Astrocytomas rarely spread to other part of the central nervous system (CNS). 1 || There is no known cause for Low Grade Astrocytomas. However, people with a family history of neurofibromatosis have a higher risk of developing these tumors. 1 ||
 * **Epidemiolgy:** || Amanuel
 * **Etiology:** || Amanuel
 * **Signs & Symptoms** || Lindsey

Signs and symptoms for CNS tumors depend on tumor location, associated expansion and surrounding edema. 2 Tumor growth along with edema may cause focal neurologic dysfunction, increased intracranial pressure and/or hydrocephalus. With significant cerebral edema or hydrocephalus, nausea and vomiting, headache, and papilledema (swelling of the optic nerve caused by increased intracranial pressure) are common. Headaches may be worse in the morning and focal neurologic deficits are also common. Long term increased intracranial pressure may lead to optic atrophy and even blindness. Seizures are also common, usually with low grade neoplasms. Lumbar back pain, bowel or bladder dysfunction may suggest lumbar metastasis. ||
 * **Diagnostic Procedures:** || Lindsey

Initial workup for CNS tumors includes a complete history and physical. 2 Following history and physical, a complete neurological exam should be performed including assessment of mental condition, cranial nerves, coordination/cerebellar function, sensation, power and reflexes. Ophthalmoscopy checks for papilledema as a sign of increased intracranial pressure should also be done. For MRI, T1 weighted images with and without gadolinium contrast, T2 weighted images, and fluid attenuated inversion recovery (FLAIR) images are all most useful. T1 weighted images show anatomy more clearly as well as areas of contrast enhancement. T2 and FLAIR images are more sensitive for detecting edema and tumor hyperintensity. CT with contrast is also useful. Staging of the neuraxis is essential for neoplasms at high risk of spread to cerebrospinal fluid (CSF). Neuraxis imaging is usually achieved with gadolinium enhanced MRI of the spine. Spinal imaging is usually combined with CSF cytology for complete neuraxis staging. Biopsy is also recommended for CNS tumors. However, selected patients with imaging and symptoms consistent with low grade glioma may be followed closely without biopsy. || These tumors may have endothelial proliferation and marked atypia; nevertheless they are slow growing and well circumscribed. 3 The different types of histology of Low-Grade Astrocytoma are listed below. 3 Protoplasmic Fibrillary Pilocytic Gemistocytic Pilomyxoid Pelomorphic Xanthoastrocytoma Absence of lymphatics in the brain; therefore no lymphatic drainage due to the blood brain barrier. || Tumor spread, when it occurs, is usually contiguous extension; dissemination to other CNS sites is uncommon, but it does occur. 4 || The World Health Organization (WHO) grading system has four categories of tumors.
 * **Histology:** || Kevin
 * Usually cortical
 * Abundant cytoplasm
 * Most common histological variant
 * Diffuse or circumscribed
 * Well-differentiated
 * Pilocytes
 * Hair-like glial processes
 * Well-differentiated
 * Cerebral hemispheres
 * Large, round cells
 * Eosinophilic cytoplasm
 * More aggressive subset of JPA’s
 * Previously identified as JPA’s
 * Primarily in the hypothalamic region
 * Peripheral hemispheric lesions
 * Often involve leptomeninges
 * More aggressive histology
 * Rare
 * Unique to children ||
 * **Lymph node drainage:** || Kevin
 * **Metastatic spread:** || Jenn
 * **Grading:** || Jenn

Grade I: tumors are slow growing; non-malignant, and associated with long term survival (pilocytic astrocytoma).

Grade II: tumors are relatively slow growing but sometimes recur as higher-grade tumors. They can be nonmalignant or malignant **(low grade astrocytoma).**

Grade III: tumors are malignant and often recur as high-grade tumors (anaplastic astrocytoma).

Grade IV: tumors reproduce rapidly and are very aggressive malignant tumors (glioblastoma). 5 ||
 * **Staging:** || Rachel

The grade of the tumor is used in place of a staging system to plan cancer treatment. There is no standard staging system for astrocytoma. Treatment is based on the grade of the tumor, and whether it is untreated or recurrent. 6 ||
 * **Radiation side effects:** || Rachel

Radiation therapy may result in substantial intellectual and endocrinologic sequelae, cerebrovascular damage, and possibly an increased risk of secondary tumors. 6 Children may be at higher risk for radiation-induced secondary tumors and morbidity due to vascular changes. ||
 * **Prognosis:** || Brandon

Low Grade Astrocytomas overall have a very high survival rate. There are multiple factor that go into determining the survival rate such as:


 * age at time of diagnosis
 * histology of tumor
 * Karnofsky Performance Score (KPS)

These factors play a critical role in a patient’s overall survival with patients that are older, have a higher grade, and have a lower KPS will have a worse prognosis. As a result of surgery, patients that are able to have complete resection have a better prognosis when compared to patients that have a partial resection in conjunction with external beam radiation therapy (EBRT). 7 ||
 * **Treatments:** || Brandon

Treatment is pretty standard for Low Grade Astrocytomas. The primary treatment of choice is surgery. 8 Depending on the outcome of surgery (complete resection or subtotal resection), will determine if more therapy is needed. If the tumor is completely resected, no more therapy is needed for the patient as they will just be observed. However, if the tumor does progress later in time, than EBRT will be used for adjuvant treatment. If the tumor is not fully resected, EBRT will be administered weeks after the surgery. Typically the doses for both treatments are the same. It is recommended that 50-55 Gray (Gy) be delivered in 1.8 - 2.0 Gy per fraction for 5 to 6 weeks. 7 It should be noted that depending on tumor site, the Organs at Risk (OR) may include the lens of the eye, optic nerve, optic chiasm, brainstem, parotid galnd(s), and spinal cord. 9 || The TD 5/5 is representative of the dose for 5% complication rate in 5 years. 10 *Note: The information above is indicative of total organ limitations. ||
 * **TD 5/5:** || Ashley
 * Lens: 1000cGy (Cataract)
 * Retina: 4500cGy (Blindness)
 * Optic Nerve: 5000cGy (Blindness)
 * Optic Chiasm: 5000cGy (Blindness)
 * Cochlea: 5500cGy
 * Pituitary: 4500cGy (Hypopituitarism)
 * Brainstem: 5000cGy (Infarction, Necrosis)
 * Spinal Cord: 4700cGy (Infarction, Necrosis)
 * Brain: 4500cGy (Infarction, Necrosis)
 * **References:** || Ashley
 * 1) Astrocytoma. American brain tumor association. []. Accessed June 3, 2013.
 * 2) Chao KS, Perez CA, Brady LW. //Radiation Oncology Management Decisions//. 3rd ed. Philadelphia, PA: Lippincott, Williams, and Wilkins; 2011: 148-149.
 * 3) Jallo GI. //Low-Grade Astrocytoma//. eMedicine. Available at: [] . Accessed: June 5, 2013.
 * 4) National Cancer Institute. Available at : [|http://www.cancer.gov/cancertopics/pdq/treatment/child-astrocytomas/HealthProfessional/page1#Section_118]. Accessed June 6, 2013.
 * 5) The new WHO classification of Tumors affecting the Central Nervous System. Available at: []. Accessed June 6, 2013.
 * 6) Childhood Astrocytomas Treatment. National Cancer Institute. Available at: [] Accessed June7, 2013.
 * 7) Pedersen C, Romner B. Current treatment of low grade astrocytoma: A review. Clin Neurol nd Neurosurg. 2013;115(1):1-8. []. Accessed 6/6/13.
 * 8) Chao K, Perez C, Brady L. //Radiation Oncology Management Decisions//. 2 nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2002.
 * 9) Washington C, Leaver D. Principle and Practice of Radiation Therapy. 3rd ed. St Louis, MO. Mosby Elsevier; 2010.
 * 10) Hall, E. //Radiobiology for the Radiologist//. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2012. ||

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