Anaplastic+Astrocytoma


 * **Epidemiolgy:** || The incidence rate of anaplastic astrocytomas is approximately 3.6 per 100,000 per year. 90% of these are symptomatic. They comprise 4% of brain tumors. The age specific rate for anaplastic astrocytomas was highest in those persons in the 75- to 84-year-old age group. [1] ||
 * **Etiology:** || Ionizing radiation and immunosuppression are risk factors. Astrocytomas occurring in an irradiation portal are sevenfold in those who survived more than three years after treatment for childhood malignancies with high radiotherapy doses. Syndromes such as Cowden’s syndrome, Li-Fraumeni and Neurofibromatosis type 1 are autosomal dominant and can be associated with astrocytomas. Li-Fraumeni is associated with a p53 germline mutation. Approximately 12% of families with this germline mutation have brain tumors. Other risk factors implicated but not yet proven include the ingestion of nitrosamines, work in the petroleum industry, exposure to electromagnetic radiation, and ingestion of aspartame. [1] ||
 * **Signs & Symptoms:** || General symptoms can include seizures, headaches, weakness or numbness, depression, nausea due to the increase of pressure within the skull. [1] Depending on specific tumor location symptoms may include limb numbness, memory loss, vision changes, and mood or personality changes. ||
 * **Diagnostic Procedures:** || CT, PETCT and MRI. MRI rendering the better of the two images due to the attenuation of the tumor verse surrounding tissue, CT without contrast will not show extent of tumor. A biopsy of the tumor can be done as well to confirm the staging.[1] ||
 * **Histology:** || Anaplastic Astrocytoma histology is [2]
 * Poorly differentiated or high-grade tumors
 * Highly cellular neoplasms that are mitotically active and have potential for metastasis
 * Clinically aggressive Anaplastic Astrocytoma with high cellularity with marked nuclear atypia[3].

|| The RTOG uses a staging system taking into account; age, Karnofsky performance, histology, mental status, extent of surgery, time between symptoms and treatment onset, neurologic function, and radiation therapy doses. [4] Yet another multifaceted system with room for error. Attatched is a karnofsky performance scale.  || Typically, anaplastic astrocytomas are treated with surgery, radiotherapy, and adjuvant chemotherapy. A majority of the time surgery is used to debulk the tumor. Total removal of the tumor is usually not possible because of the invasion of critical structures in the brain.[6] Radiation fields would include the tumor and adema with 3 cm. margins. The dose given would be 60-64 Gy, in 1.8-2 Gy daily fractions. Palliation is 30 Gy for symptom control.[5] || || 2. Pediatric Oncology Education Material. //Astrocytoma//. Available at: []. Accessed: May 30, 2012. 3. Kennedy B. //Astrocytoma//. Emedicine. 2012. Available at: [|http://emedicine.medscape.com/article/283453-workup#a0723]. Accessed: June 1, 2012. 4. Washington, Charles M. //Principles and Practice of Radiation Therapy.// Third ed. St. Louis: Mosby; 2010 5. Chao, K.S. Clifford //Radiation Oncology Management Decisions.// Third ed. Philadelphia: LWW; 2011 6. Kennedy B, Harris J, Bruce JN, et al. Astrocytoma. [|http://emedicine.medscape.com/article/283453-overview#showall]. Jan. 17,2012. Accessed May 31, 2012. 7. Emami B, Lyman J, Brown A, et al. Tolerance of normal tissue to therapeutic irradiation. //Int J Radiat Oncol Biol Phys.// 1991;109-122. []. Accessed May 31, 2012. || Back to Week 2
 * **Lymph node drainage:** || Since there is an absence of lymphatics in the brain, there is no lymphatic drainage due to the blood brain barrier[2]. ||
 * **Metastatic spread:** || Unlike other systemic tumors, metastasis of Astrocytomas is exceedingly rare. Clinical decline and tumor associated morbidity and mortality are almost always associated with local mass effects on the brain by a locally recurrent intracranial tumor[2]. ||
 * **Grading:** || The grade of a tumor is based on its aggressiveness of growth and cellular differentiation. Grade is determined by microscopic examination of tumor cells and is important in predicting the prognosis of a CNS tumor diagnosis. Grade and stage give the physician an accurate description of the tumor so that they may treat it effectively. CNS tumors can be grouped in to benign, low-grade or malignant, and high grade. A system known as the Kernohan Grading System, which is a four grade system has also been used. This system takes in to consideration; cellularity, anaplasia, mitotic figures, giant cells, necrosis, blood vessels and proliferation. Because of the many factors, this grading system is confusing and difficult to use.[4] ||
 * **Staging:** || There are no universal staging systems for CNS tumors which can be confusing and can lead to problems when diagnosing. The American Joint Committee on Cancer uses a GTM system; grade (G), Tumor type (T), and Metastasis (M).
 * **Radiation side effects:** || Depending on the location, treatment type, and extent of expansion around the tumor site, many side effects are possible but not all likely. Many of them include:
 * Nausea vomiting
 * Radiation dermatitis
 * Hair loss in treatment field
 * Inflammation of outer middle or inner ear and other ear damage, if in the treatment area, may cause temporary or permanent hearing loss.
 * Fatigue
 * Blood counts may decrease with large treatment volumes
 * Somnolence syndrome, occurs 6-12 weeks post radiation caused by damage to oligodendroglial cells.
 * <span style="color: #7030a0; font-family: 'Times New Roman','serif'; font-size: 16px;">Focal radiation necrosis can appear 6 months to years post radiation.
 * <span style="color: #7030a0; font-family: 'Times New Roman','serif'; font-size: 16px;">Cataracts, retinopothy if eye is included in field
 * <span style="color: #7030a0; font-family: 'Times New Roman','serif'; font-size: 16px;">Visual degradation if the optic nerve and or chiasm are included with blindness at doses of 50 to 55 Gy.
 * <span style="color: #7030a0; font-family: 'Times New Roman','serif'; font-size: 16px;">Hypothalamic-pituitary doses of 20 Gy or more can cause insuficiant hormone production. Brain irradiation can impact critical thinking, short term memory, and learning ability.[5] ||
 * **Prognosis:** || Anaplastic astrocytomas are a grade III tumor. They are aggressive and invade normal brain tissue and even spread outside the central nervous system. Average survival is 2-5 years.[6] ||
 * **Treatments:** || [[image:uwlmedicaldosimetry2012/anaastro.jpg width="413" height="436" caption="Anaplastic Astrocytoma"]]
 * **TD 5/5:** || ** TD 5/5 values from Emami 1991 [7] **
 * **References** || 1. Lenhard RE, Osteen R, Gansler T. //The American Cancer Society’s Clinical Oncology//. Williston, VT: Blackwell Publishing, Inc; 2001.