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PubMed This is a summary of 102 peer-reviewed journal articles Updated
Neuro-oncology · Glioma

Understanding Your Glial Tumor (Glioma) Diagnosis

At a Glance

A glioma is a primary brain tumor that begins in the brain's supportive cells. Today, gliomas are classified by their unique DNA and genetic markers, such as the IDH mutation. This specific molecular profile helps your care team build a personalized and highly targeted treatment roadmap.

A diagnosis of a glioma (glial tumor) can feel overwhelming, but understanding the biology of your tumor is the first step toward regaining a sense of control. Unlike many other cancers that are defined by where they are in the body, modern neuro-oncology identifies gliomas primarily by their “DNA signature” or molecular makeup [1][2]. This shift means that your care team is focusing on the specific biology of your tumor to create a personalized treatment roadmap [3].

What is a Glioma?

A glioma is a type of primary brain tumor, meaning it begins in the brain rather than spreading there from another part of the body [4]. These tumors arise from glial cells, which are the “supportive cells” of the nervous system [5]. While neurons (nerve cells) transmit electrical signals, glial cells provide the essential structure, nutrition, and insulation those neurons need to function [5].

When glial cells become cancerous, they can grow into different types of gliomas:

  • Astrocytomas: Arise from star-shaped cells called astrocytes [5].
  • Oligodendrogliomas: Arise from cells that create the protective coating (myelin) around nerve fibers [5].
  • Glioblastomas: A more aggressive form of glioma [2].

The DNA-First Approach (2021 WHO Classification)

In the past, doctors looked at tumor cells under a microscope to decide what type they were. However, as of the 2021 WHO Classification, the biology (genetics) of the tumor is now more important than its appearance [1][6].

Your doctors will look for specific “markers” to classify your tumor:

  • IDH Mutation: Whether your tumor has a mutation in the IDH gene is the single most important factor in determining the tumor type and how it might behave [2][7].
  • 1p/19q Codeletion: Doctors check if two specific pieces of chromosomes are missing, which helps identify oligodendrogliomas [2][8].
  • Molecular Grading: Even if a tumor looks less aggressive under a microscope, certain genetic markers (like CDKN2A/B deletions) can change its grade to a 4, ensuring you receive the most appropriate level of care [9][10].

For a deep dive into reading your reports, see Decoding Your Glioma Pathology Report: IDH, 1p/19q, and WHO Grades.

Stabilization Facts

It is natural to feel a range of intense emotions following this diagnosis. Here are several facts to help stabilize your perspective as you begin this journey:

01

Treatment Strategy: Surgery, Radiation, and Medical Therapies for Gliomas

Learn about glioma treatment options including maximal safe resection, radiation, the Stupp Protocol, and targeted therapies like Vorasidenib for IDH mutations.

02

Building Your Neuro-Oncology Care Team and Preparing for Visits

Learn how to build an expert neuro-oncology care team for a glioma diagnosis. Understand tumor boards, how to vet doctors, and tips for managing scanxiety.

Common Misunderstandings

  • “Grade” vs. “Stage”: In many cancers (like breast or lung cancer), doctors use “stages” (1-4) to describe how far the cancer has spread in the body. For brain tumors, we use grades (1-4) to describe how fast the cells are growing and how they behave [16][17].
  • “Brain Cancer” vs. “Glioma”: Not all brain tumors are gliomas. For example, a meningioma starts in the lining of the brain and behaves very differently than a glioma [4]. Understanding that yours is a glioma helps target the right treatments.
  • Readability of Information: Many medical documents are written in complex jargon that can increase anxiety [18]. If a report or explanation is confusing, it is the team’s job to translate it into terms you can use to make decisions.

For practical daily advice, see Managing Symptoms and Quality of Life: Seizures, Swelling, and Fatigue.

Common questions in this guide

What is a glioma?
A glioma is a type of primary brain tumor that starts in the glial cells, which are the supportive cells of the nervous system. Instead of spreading from another part of the body, these tumors originate directly in the brain.
How do doctors determine the grade of my brain tumor?
Doctors grade brain tumors from 1 to 4 based on how fast the cells are growing and how they behave. Following the 2021 WHO guidelines, your medical team will look at the tumor's DNA and genetic markers, such as the IDH mutation, to accurately determine its grade.
What is the difference between a brain tumor grade and a stage?
While many cancers use stages to describe how far the disease has spread throughout the body, primary brain tumors use grades. Grades describe how aggressively the tumor cells are growing and behaving within the brain itself.
Why is the IDH mutation important in my glioma diagnosis?
The IDH mutation is a crucial genetic marker that helps doctors identify your specific type of glioma and understand its behavior. Knowing your IDH mutation status is the single most important factor your medical team uses to create your personalized treatment plan.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.What is the specific molecular profile of my tumor, including IDH mutation and 1p/19q codeletion status?
  2. 2.How does the 2021 WHO classification specifically change the way my tumor is graded and treated?
  3. 3.Has my case been reviewed by a multidisciplinary team (MDT) or tumor board?
  4. 4.What are the next steps in my treatment roadmap, and what is the primary goal of the first phase?
  5. 5.Are there specific clinical trials available for my exact molecular subtype of glioma?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (18)
  1. 1

    Classification and Diagnosis of Adult Glioma: A Scoping Review.

    Byun YH, Park CK

    Brain & NeuroRehabilitation 2022; (15(3)):e23 doi:10.12786/bn.2022.15.e23.

    PMID: 36742083
  2. 2

    Implications of molecular classifications in glioma surgery.

    Kalluri AL, Lee JH, Lucas CG, et al.

    Journal of neuro-oncology 2025; (171(3)):559-569 doi:10.1007/s11060-024-04883-0.

    PMID: 39532825
  3. 3

    Effect of High-Quality Nursing Based on Comprehensive Nursing on the Postoperative Quality of Life and Satisfaction of Patients with Malignant Glioma.

    Gong X, Wu W, Xing D, et al.

    Evidence-based complementary and alternative medicine : eCAM 2022; (2022()):9345099 doi:10.1155/2022/9345099.

    PMID: 35529933
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    Evaluation of VEGF, FGF and PDGF and Serum Levels of Inflammatory Cytokines in Patients with Glioma and Meningioma in Southern Iran.

    Shamsdin SA, Mehrafshan A, Rakei SM, Mehrabani D

    Asian Pacific journal of cancer prevention : APJCP 2019; (20(10)):2883-2890 doi:10.31557/APJCP.2019.20.10.2883.

    PMID: 31653130
  5. 5

    Context-dependent regulation of Notch signaling in glial development and tumorigenesis.

    Guo R, Han D, Song X, et al.

    Science advances 2023; (9(45)):eadi2167 doi:10.1126/sciadv.adi2167.

    PMID: 37948517
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    Classification of adult-type diffuse gliomas: Impact of the World Health Organization 2021 update.

    Whitfield BT, Huse JT

    Brain pathology (Zurich, Switzerland) 2022; (32(4)):e13062 doi:10.1111/bpa.13062.

    PMID: 35289001
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    miRNAs and related genetic biomarkers according to the WHO glioma classification: From diagnosis to future therapeutic targets.

    Nikolova E, Laleva L, Milev M, et al.

    Non-coding RNA research 2024; (9(1)):141-152 doi:10.1016/j.ncrna.2023.10.003.

    PMID: 38035044
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    HIP1R and vimentin immunohistochemistry predict 1p/19q status in IDH-mutant glioma.

    Felix M, Friedel D, Jayavelu AK, et al.

    Neuro-oncology 2022; (24(12)):2121-2132 doi:10.1093/neuonc/noac111.

    PMID: 35511748
  9. 9

    A multi-center, clinical analysis of IDH-mutant gliomas, WHO Grade 4: implications for prognosis and clinical trial design.

    Wetzel EA, Nohman AI, Hsieh AL, et al.

    Journal of neuro-oncology 2025; (171(2)):373-381 doi:10.1007/s11060-024-04852-7.

    PMID: 39432026
  10. 10

    Improved prognostic stratification of patients with isocitrate dehydrogenase-mutant astrocytoma.

    Weller M, Felsberg J, Hentschel B, et al.

    Acta neuropathologica 2024; (147(1)):11 doi:10.1007/s00401-023-02662-1.

    PMID: 38183430
  11. 11

    Nursing Guide to Management of Major Symptoms in Patients with Malignant Glioma.

    Siegel C, Armstrong TS

    Seminars in oncology nursing 2018; (34(5)):513-527 doi:10.1016/j.soncn.2018.10.014.

    PMID: 30424920
  12. 12

    CBTRUS Statistical Report: Primary Brain and Other Central Nervous System Tumors Diagnosed in the United States in 2015-2019.

    Ostrom QT, Price M, Neff C, et al.

    Neuro-oncology 2022; (24(Suppl 5)):v1-v95 doi:10.1093/neuonc/noac202.

    PMID: 36196752
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    Workforce Challenges for the Neurosurgical Care of Brain Tumors in Low- and Middle-Income Countries: A Scoping Review.

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    World neurosurgery 2024; (189()):387-398.e3 doi:10.1016/j.wneu.2024.06.098.

    PMID: 38925244
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    National-level overall survival patterns for molecularly-defined diffuse glioma types in the United States.

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    Neuro-oncology 2023; (25(4)):799-807 doi:10.1093/neuonc/noac198.

    PMID: 35994777
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    Molecular marker testing and reporting completeness for adult-type diffuse gliomas in the United States.

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    PMID: 36659967
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    Canine Gliomatosis Cerebri: Morphologic and Immunohistochemical Characterization Is Supportive of Glial Histogenesis.

    Rissi DR, Donovan TA, Porter BF, et al.

    Veterinary pathology 2021; (58(2)):293-304 doi:10.1177/0300985820980704.

    PMID: 33357125
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    Extent of Resection of Glioblastoma: A Critical Evaluation in the Molecular Era.

    Cahill DP

    Neurosurgery clinics of North America 2021; (32(1)):23-29 doi:10.1016/j.nec.2020.09.006.

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  18. 18

    Readability of Online Neuro-Oncology-Related Patient Education Materials from Tertiary-Care Academic Centers.

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This page provides an educational overview of glioma diagnosis and tumor biology. It does not replace professional medical advice. Always consult your neuro-oncologist or multidisciplinary care team to discuss your specific tumor type and treatment plan.

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