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| __NOTOC__ | | __NOTOC__ |
| {{Astrocytoma}} | | {{Astrocytoma}} |
| {{CMG}} | | {{CMG}}; {{AE}} {{Fs}} |
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| ==Overview== | | ==Overview== |
| There are two broad classes of classification identified within astrocytomas, based on histology, as to whether the zones of infiltration of cancer cells are narrow or diffuse.
| | Astrocytoma may be classified according to its [[histology]] into 4 grades: [[pilocytic astrocytoma]], [[diffuse astrocytoma]], [[anaplastic astrocytoma]] and [[glioblastoma multiforme]]. |
| ==Classification== | | ==Classification== |
| Within the astrocytomas, there are two broad classes recognized in literature, those with:
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| * Narrow zones of infiltration (mostly invasive tumors; e.g., pilocytic astrocytoma, subependymal giant cell astrocytoma, pleomorphic xanthoastrocytoma), that often are clearly outlined on diagnostic images
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| * Diffuse zones of infiltration (e.g., low-grade astrocytoma, anaplastic astrocytoma, glioblastoma), that share various features, including the ability to arise at any location in the CNS, but with a preference for the cerebral hemispheres; they occur usually in adults; and an intrinsic tendency to progress to more advanced grades.<ref> http://emedicine.medscape.com/article/283453-overview </ref>
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| ===Grading=== | | * Astrocytoma may be classified according to its histology into 4 grades:<ref name="pmid3179928">{{cite journal |vauthors=Daumas-Duport C, Scheithauer B, O'Fallon J, Kelly P |title=Grading of astrocytomas. A simple and reproducible method |journal=Cancer |volume=62 |issue=10 |pages=2152–65 |date=November 1988 |pmid=3179928 |doi= |url=}}</ref><ref name="pmid27157931">{{cite journal |vauthors=Louis DN, Perry A, Reifenberger G, von Deimling A, Figarella-Branger D, Cavenee WK, Ohgaki H, Wiestler OD, Kleihues P, Ellison DW |title=The 2016 World Health Organization Classification of Tumors of the Central Nervous System: a summary |journal=Acta Neuropathol. |volume=131 |issue=6 |pages=803–20 |date=June 2016 |pmid=27157931 |doi=10.1007/s00401-016-1545-1 |url=}}</ref> |
| Astrocytomas have great variation in their presentation. The [[World Health Organization]] acknowledges the following grading system for astrocytomas:
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| * '''Grade 1''' — [[pilocytic astrocytoma]] - primarily pediatric tumor, with median age at diagnosis of 12
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| * '''Grade 2''' — diffuse astrocytoma
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| * '''Grade 3''' — anaplastic (malignant) astrocytoma
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| * '''Grade 4''' — [[glioblastoma multiforme]] (most common)
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| In addition to these four tumor grades, astrocytomas may combine with oligodendrocytes to produce [[oligoastrocytoma]]. Unique astrocytoma variants have also been known to exist.===Grading===
| | {{Family tree/start}} |
| Of numerous [[Grading of the tumors of the central nervous system|grading systems]] in use for the classification of tumor of the central nervous system, the [[World Health Organization]] [[Grading of the tumors of the central nervous system#WHO grading|(WHO) grading system]] is commonly used for astrocytoma. Established in 1993 in an effort to eliminate confusion regarding diagnoses, the WHO system established a four-tiered histologic grading guideline for astrocytomas that assigns a grade from 1 to 4, with 1 being the least aggressive and 4 being the most aggressive.
| | {{Family tree| | | | | | | | | | | | A01 | | | | | | | | | | | | |A01=Astrocytoma}} |
| | {{Family tree| | | | | |,|-|-|-|-|-|-|^|-|-|-|-|-|.| | | | | | | | | | | | }} |
| | {{Family tree| | | | | D01 | | | | | | | | | | | D02 | | | | | | | | | | |D01=Low grade|D02=High grade}} |
| | {{Family tree| | | |,|-|^|-|.| | | | | | | | |,|-|^|-|.| | | | | | | | | | | | }} |
| | {{Family tree| | | B01 | | B02 | | | | | | | B03 | | B04 | | | | | | | | | | |B01=Pilocyic astrocytoma|B02=Diffuse astrocytoma|B03=Anaplastic astrocytoma|B04=Glioblastomas multiform}} |
| | {{Family tree| |,|-|-|-|v|-|^|-|v|-|-|-|.| | | |,|-|-|^|-|-|.| | | | }} |
| | {{Family tree| C01 | | C02 | | C03 | | C04 | | | C05 | | | | C06 | | |C01=[[Fibrillary astrocytoma]]|C02=[[Gemistocytic astrocytoma]]|C03=[[Protoplasmic astrocytoma]]|C04=[[Oligoastrocytoma]]|C05=Primary glioblastoma multiforme|C06=Secondary glioblastoma multiforme}} |
| | {{Family tree/end}} |
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| The WHO-grading scheme is based on the appearance of certain characteristics: [[atypia]], [[mitosis]], endothelial proliferation, and [[necrosis]]. These features reflect the malignant potential of the tumor in terms of invasion and growth rate. Tumors without any of these features are grade I, and those with one of these features (usually atypia) are grade II. Tumors with 2 criteria and tumors with 3 or 4 criteria are WHO grades III and IV, respectively. Thus, the low-grade group of astrocytomas are grades I and II.
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| Various types of astrocytomas are given these WHO grades:
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| {| class="wikitable"
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| ! WHO Grade
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| ! Astrocytomas
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| ! Description
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| |-
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| | I
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| *[[Pilocytic astrocytoma]]
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| *[[Pleomorphic xanthoastrocytoma]]
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| *[[Subependymal giant cell astrocytoma]]
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| *Subependymoma
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| | Consist of slow growing astrocytomas, benign, and associated with long-term survival. Individuals with very slow growing tumors where complete surgical removal by [[stereotactic surgery]] is possible may experience total remission.<ref name=mdguidelines>[http://www.mdguidelines.com/astrocytoma mdguidelines.com > Astrocytoma] Retrieved on Mars 26, 2010</ref> Even if the surgeon is not able to remove the entire tumor, it may remain inactive or be successfully treated with radiation.
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| | II
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| *Low-grade ([[fibrillary astrocytoma|fibrillary]]) astrocytoma
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| *Mixed oligoastrocytoma
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| | Consist of relatively slow-growing astrocytomas, usually considered benign that sometimes evolve into more malignant or as highergrade tumors. They are prevalent in younger people who often present with seizures. Median survival varies with the cell type of the tumor. Grade 2 astrocytomas are defined as being invasive gliomas, meaning that the tumor cells penetrate into the surrounding normal brain, making a surgical cure more difficult. People with [[oligodendroglioma]]s (which might share common cells of origin<ref name=evolutionGliomas>{{cite journal |last1=Ohgaki |first1=Hiroko |last2=Kleihues |first2=Paul |title=Genetic alterations and signaling pathways in the evolution of gliomas |journal=Cancer Science |volume=100 |issue=12 |pages=2235–41 |year=2009 |pmid=19737147 |doi=10.1111/j.1349-7006.2009.01308.x }}</ref>) have better prognoses than those with mixed oligoastrocytomas, who in turn have better prognoses than patients with (pure) low-grade astrocytomas. Other factors which influence survival include age (younger the better) and performance status (ability to perform tasks of daily living). Due to the infiltrative nature of these tumors, recurrences are relatively common. Depending on the patient, radiation or chemotherapy after surgery is an option. Individuals with grade 2 astrocytoma have a 5-year survival rate of about 34% without treatment and about 70% with radiation therapy.<ref name=mdguidelines/> The median survival time is 4 years.<ref name=mdguidelines/>
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| | III
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| | [[Anaplastic astrocytoma]]
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| | Consist of anaplastic astrocytomas. It is often related to seizures, neurologic deficits, headaches, or changes in mental status. The standard initial treatment is to remove as much of the tumor as possible without worsening neurologic deficits. [[Radiation therapy]] has been shown to prolong survival and is a standard component of treatment. Individuals with grade 3 astrocytoma have a median survival time of 18 months without treatment (radiation and chemotherapy).<ref name=mdguidelines/> There is no proven benefit to adjuvant [[chemotherapy]] or supplementing other treatments for this kind of tumor. Although [[temozolomide]] is effective for treating recurrent anaplastic astrocytoma, its role as an adjuvant to radiation therapy has not been fully tested.
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| | IV
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| | [[Glioblastoma multiforme]] (GBM)
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| | Consists of Glioblastoma multiforme (GBM), which is the most common and most malignant primary brain tumor. Primary GBM grow and spread to other parts of the brain quickly; they can become very large before producing symptoms, which often begin abruptly with seizures.<ref name="mainstay">quoted from http://www.mayoclinic.org/glioma/glioblastoma.html{{full}}</ref> Less than 10% form more slowly following degeneration of low-grade astrocytoma or anaplastic astrocytoma. These are called secondary GBM and are more common in younger patients (mean age 45 versus 62 years).<ref name=evolutionGliomas /> "Surgical removal remains the mainstay of treatment, provided that unacceptable neurologic injury can be avoided. The extremely infiltrative nature of this tumor makes complete surgical removal impossible. Although radiotherapy rarely cures glioblastoma, studies show that it doubles the median survival of patients, compared to supportive care alone."<ref name="mainstay" /> The prognosis is worst for these grade 4 gliomas. Few patients survive beyond 3 years. Individuals with grade 4 astrocytoma have a median survival time of 17<ref name=mdguidelines/> weeks without treatment, 30<ref name=mdguidelines/> weeks with radiation, and 37<ref name=mdguidelines/> weeks with surgical removal of most of the tumor followed by radiation therapy. Long-term survival (at least five years) falls well under 3%.<ref name=Buckner>{{cite journal |last1=Buckner |first1=Jan C. |last2=Brown |first2=Paul D. |last3=O'Neill |first3=Brian P. |last4=Meyer |first4=Fredric B. |last5=Wetmore |first5=Cynthia J. |last6=Uhm |first6=Joon H. |title=Central Nervous System Tumors |journal=Mayo Clinic Proceedings |volume=82 |issue=10 |pages=1271–86 |year=2007 |pmid=17908533 |doi=10.4065/82.10.1271 }}</ref><ref name=CBTRUS>Central Brain Tumor Registry of the United States, http://www.cbtrus.org/</ref>
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| |}
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| According to the WHO data the lowest grade astrocytomas (grade I) make up only 2% of recorded astrocytomas, grade II 8%, and the higher grade anaplastic astrocytomas (grade III) 20%. The highest graded astrocytoma (grade IV GBM) is the most common primary [[nervous system neoplasm|nervous system cancer]] and second most frequent brain tumor after brain metastasis. Despite the low incidence of astrocytomas compared to other human cancers, mortality is significant, as the higher grades (III & IV) present high mortality rates (mainly due to late detection of the neoplasm).
| | * Low-grade astrocytoma may be classified based on tumor spread into four subtypes including: |
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| ==See Also==
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| {{main|pilocytic astrocytoma|glioblastoma multiforme}}
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| | {{familytree/start |summary=Low grade astrocytoma}} |
| | {{familytree | | | | | | | | | | | | | A01| | | | | | | | | | | | | |A01=Low-grade astrocytoma}} |
| | {{familytree | | | | | | | |,|-|-|-|-|-|^|-|-|-|-|-|.| | | | | | | |}} |
| | {{familytree | | | | | | | B01 | | | | | | | | | | B02 | | | | | | | | |B01=[[Localized low-grade astrocytoma]]|B02=Low-grade infiltrative astrocytoma<br>Diffuse astrocytoma}} |
| | {{familytree | | | | | | | F01 | | | | | | | | | | F02 | | | | | | | | |F01=WHO grade I / II|F02=WHO grade II}} |
| | {{familytree | | | | | | | |!| | |,|-|-|-|v|-|-|-|v|^|-|.| | | | | | | |}} |
| | {{familytree | | | | | | | |!| | C01 | | C02 | | C03 | | C04 | | | | | |C01=[[Fibrillary astrocytoma]]|C02=[[Gemistocytic astrocytoma]]|C03=[[Protoplasmic astrocytoma]]|C04=[[Oligoastrocytoma]]}} |
| | {{familytree | |,|-|-|-|v|-|^|-|v|-|-|-|.| | | | | | | | | | | | | | |}} |
| | {{familytree | D01 | | D02 | | D03 | | D04 | | | | | | | | | | | | | | |D01=[[Pilocytic astrocytoma]]|D02=Pilomyxoid astrocytoma|D03=[[Subependymal giant cell astrocytoma]]|D04=[[Pleomorphic xanthoastrocytoma]]}} |
| | {{familytree | E01 | | E02 | | E03 | | E04 | | | | | | | | | | | | | |E01=WHO grade I|E02=WHO grade II|E03=WHO grade I|E04=WHO grade II}} |
| | {{familytree/end}} |
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| ==References== | | ==References== |
| {{reflist|2}} | | {{reflist|2}} |
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| {{WH}}
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| {{WS}}
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| [[Category:Disease]] | | [[Category:Disease]] |
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| [[Category:Pathology]] | | [[Category:Pathology]] |
| [[Category:Neurosurgery]] | | [[Category:Neurosurgery]] |
| | [[Category:Up-To-Date]] |
| | [[Category:Oncology]] |
| | [[Category:Medicine]] |