Glossary

Glioma glossary

Every term in the Glioma glossary — 265 plain-language definitions across 11 sections, each with its own page.

Core Terms & Classification

Glioma: A glioma is a tumor that arises from the glial cells of the brain or spinal cord, the most common type of primary brain tumor.
Brain tumor: A brain tumor is an abnormal growth of cells in or around the brain, which may be benign or malignant and may begin in the brain or spread from elsewhere.
Primary brain tumor: A primary brain tumor is one that begins in the brain itself, as opposed to spreading there from cancer elsewhere; gliomas are primary brain tumors.
Metastatic (secondary) brain tumor: A metastatic brain tumor is cancer that has spread to the brain from elsewhere in the body, distinct from a glioma, which begins in the brain.
Central nervous system (CNS) tumor: A central nervous system tumor is a tumor of the brain or spinal cord, the category that includes gliomas under the WHO classification.
Glial cells: Glial cells are the supportive cells of the nervous system that surround and assist neurons, and the cells from which gliomas arise.
Neoplasm: A neoplasm is an abnormal, excessive growth of cells, the general medical term for a tumor, including gliomas.
Benign versus malignant (brain tumors): Benign and malignant describe whether a tumor is non-cancerous or cancerous, though in the brain even benign tumors can cause problems by their location.
Diffuse glioma: A diffuse glioma is a glioma that infiltrates surrounding brain tissue, the most common and clinically important category of glioma in adults.
Circumscribed glioma: A circumscribed glioma is a glioma with relatively well-defined borders that does not widely infiltrate the brain, often more amenable to surgery.
WHO Classification of CNS Tumors: The WHO Classification of Tumors of the Central Nervous System is the international standard system for naming, grouping, and grading brain and spinal cord tumors, including gliomas.
WHO CNS5 (2021 classification): WHO CNS5 is the 2021 fifth edition of the brain tumor classification, which for the first time integrates molecular markers into how gliomas are defined and graded.
Tumor grade: Tumor grade is a measure of how aggressive a tumor is expected to be, based on its appearance and molecular features, central to predicting glioma behavior.
WHO grade (1–4): WHO grades 1 to 4 indicate increasing aggressiveness of a glioma, with grade 1 the least aggressive and grade 4 the most aggressive.
Low-grade glioma: A low-grade glioma is a slower-growing glioma (generally grade 1 or 2), often with a more favorable outlook than high-grade gliomas.
High-grade glioma: A high-grade glioma is a faster-growing, more aggressive glioma (generally grade 3 or 4), which requires prompt and intensive treatment.
Histopathology (histology): Histopathology is the examination of tumor tissue under a microscope, a foundational step in diagnosing and grading gliomas.
Integrated (layered) diagnosis: An integrated diagnosis combines microscopic and molecular findings into a single, precise glioma diagnosis, the standard approach in the modern WHO system.
Adult-type diffuse glioma: Adult-type diffuse gliomas are the main group of infiltrating gliomas in adults, comprising IDH-mutant astrocytoma, IDH-mutant oligodendroglioma, and IDH-wildtype glioblastoma.
Pediatric-type diffuse glioma: Pediatric-type diffuse gliomas are infiltrating gliomas with the distinct biology typically seen in children, divided into low-grade and high-grade groups.
Astrocytoma (overview): An astrocytoma is a glioma arising from astrocyte-like cells, ranging from low-grade tumors to grade 4, and defined in adults largely by IDH status.
Oligodendroglioma (overview): An oligodendroglioma is a glioma defined by an IDH mutation together with 1p/19q codeletion, generally carrying the most favorable outlook among adult diffuse gliomas.
Glioblastoma (overview): Glioblastoma is the most aggressive and most common malignant primary brain tumor in adults, now defined as an IDH-wildtype, grade 4 diffuse astrocytic glioma.
Ependymoma (overview): An ependymoma is a glioma arising from ependymal cells lining the brain's fluid spaces, a distinct type from the diffuse gliomas, often more circumscribed.

Cell Types, Anatomy & Tumor Biology

Astrocytes: Astrocytes are star-shaped glial cells that support neurons and the blood-brain barrier, the cell type that astrocytomas resemble.
Oligodendrocytes: Oligodendrocytes are glial cells that form the insulating myelin around nerve fibers, the cell type that oligodendrogliomas resemble.
Ependymal cells: Ependymal cells line the fluid-filled spaces of the brain and spinal cord, the cell type that ependymomas arise from.
Neurons (and glioma): Neurons are the signaling cells of the nervous system; gliomas arise not from neurons but from the glial cells that support them.
Glial precursor / stem-like cells: Glial precursor or stem-like cells are immature cells that can give rise to glial cells, thought to be a source of gliomas and a focus of research.
White matter: White matter is the part of the brain made of myelinated nerve fibers, the tissue through which diffuse gliomas often spread.
Gray matter: Gray matter is the part of the brain rich in nerve cell bodies, where much of the brain's processing occurs and where some gliomas arise.
Cerebrum / cerebral hemispheres: The cerebrum is the largest part of the brain, divided into two hemispheres, and the most common location for gliomas in adults.
Frontal lobe (and glioma): The frontal lobe controls movement, personality, and executive functions; gliomas here can affect these abilities.
Temporal lobe (and glioma): The temporal lobe handles memory, hearing, and aspects of language; gliomas here can affect these functions and often cause seizures.
Parietal lobe (and glioma): The parietal lobe processes sensation and spatial awareness; gliomas here can affect these functions.
Occipital lobe (and glioma): The occipital lobe processes vision; gliomas here can affect sight and visual perception.
Brainstem (and glioma): The brainstem controls vital functions and connects the brain to the spinal cord; gliomas here are especially challenging due to the critical structures involved.
Cerebellum (and glioma): The cerebellum coordinates movement and balance; gliomas here, more common in children, can affect coordination.
Spinal cord glioma: A spinal cord glioma is a glioma arising in the spinal cord, less common than brain gliomas and causing symptoms related to spinal cord function.
Corpus callosum (butterfly glioma): The corpus callosum connects the two cerebral hemispheres; a glioma spreading across it, forming a "butterfly" shape, indicates aggressive infiltration.
Blood-brain barrier: The blood-brain barrier is a protective filter between the bloodstream and the brain, which can limit how well drugs reach a glioma.
Tumor microenvironment: The tumor microenvironment is the surrounding cells, blood vessels, and signals that interact with a glioma, influencing its growth and response to treatment.
Angiogenesis (in glioma): Angiogenesis is the growth of new blood vessels that tumors use to supply themselves, a prominent feature of aggressive gliomas and a treatment target.
Necrosis (in glioma): Necrosis is dead tumor tissue, a feature of aggressive gliomas that helps define grade 4 tumors such as glioblastoma.
Microvascular proliferation: Microvascular proliferation is the growth of abnormal tumor blood vessels, a microscopic hallmark used to identify grade 4 gliomas.
Infiltration / invasion: Infiltration is the spread of glioma cells into surrounding normal brain tissue, the defining behavior of diffuse gliomas that makes complete removal difficult.
Mitotic activity (proliferation): Mitotic activity is how rapidly tumor cells are dividing, a key indicator of a glioma's grade and aggressiveness.
Ki-67 / proliferation index: The Ki-67 (proliferation) index is a measure of how many tumor cells are actively dividing, helping assess a glioma's aggressiveness.

Molecular & Genetic Markers

IDH (isocitrate dehydrogenase) mutation: An IDH mutation is a change in the IDH gene that is central to classifying diffuse gliomas and is associated with a generally better outlook.
IDH1 versus IDH2: IDH1 and IDH2 are the two genes in which glioma-related IDH mutations occur, with IDH1 being far more common.
IDH-mutant (tumor designation): IDH-mutant designates a glioma carrying an IDH mutation, defining it as an astrocytoma or oligodendroglioma with a generally favorable outlook.
IDH-wildtype (tumor designation): IDH-wildtype designates a glioma without an IDH mutation; in adult diffuse astrocytic tumors, this defines glioblastoma.
2-hydroxyglutarate (oncometabolite): 2-hydroxyglutarate is an abnormal substance produced by mutant IDH enzymes that drives glioma development and is the target of IDH inhibitor drugs.
1p/19q codeletion: 1p/19q codeletion is the loss of segments of chromosomes 1 and 19 that, with an IDH mutation, defines oligodendroglioma and predicts a favorable treatment response.
MGMT promoter methylation: MGMT promoter methylation is a chemical change that quiets a DNA-repair gene, making glioblastoma more responsive to the chemotherapy drug temozolomide.
TERT promoter mutation: A TERT promoter mutation is a genetic change that helps tumor cells keep dividing and is one of the markers that can define glioblastoma.
EGFR amplification: EGFR amplification is an excess of copies of a growth-signaling gene that drives tumor growth and is one of the markers that can define glioblastoma.
Chromosome 7 gain / 10 loss (+7/−10): Combined chromosome 7 gain and 10 loss is a chromosomal change common in glioblastoma and one of the markers that can define it.
CDKN2A/B homozygous deletion: CDKN2A/B homozygous deletion is the loss of both copies of tumor-suppressor genes that, in certain gliomas, raises the grade to 4.
ATRX loss: ATRX loss is the loss of a gene's normal function that, with an IDH mutation, helps identify an astrocytoma rather than an oligodendroglioma.
TP53 mutation: A TP53 mutation is a change in a key tumor-suppressor gene that is common in IDH-mutant astrocytomas and other gliomas.
H3 K27M (H3 K27-altered): H3 K27M is a mutation in a histone gene that defines diffuse midline glioma, a serious grade 4 tumor occurring mainly in children.
H3 G34 mutation: An H3 G34 mutation is a histone gene change that defines diffuse hemispheric glioma, a high-grade tumor occurring in adolescents and young adults.
BRAF V600E mutation: A BRAF V600E mutation is a growth-pathway change found in some gliomas — particularly certain pediatric ones — that can be targeted by specific drugs.
KIAA1549::BRAF fusion: The KIAA1549::BRAF fusion is a gene rearrangement that drives most pilocytic astrocytomas and predicts a favorable outcome.
MAPK/ERK pathway: The MAPK/ERK pathway is a cell growth-signaling system whose abnormal activation drives many pediatric low-grade gliomas.
Methylation profiling (DNA methylation classification): Methylation profiling is an advanced test that classifies brain tumors by their pattern of chemical DNA marks, improving diagnostic accuracy.
Next-generation sequencing: Next-generation sequencing is a technology that rapidly reads many genes at once, used to detect the mutations that classify and guide glioma treatment.
Immunohistochemistry: Immunohistochemistry is a tissue-staining technique that detects specific proteins, used to identify markers like IDH mutation and ATRX loss in gliomas.
Molecular biomarker (prognostic versus predictive): A molecular biomarker is a measurable feature of a tumor; prognostic markers indicate likely outcome, while predictive markers indicate likely response to a treatment.
Driver mutation: A driver mutation is a genetic change that actively promotes a tumor's growth, often the key target for treatment.
Oncogene: An oncogene is a gene that, when overactive, promotes cancer growth; several oncogenes are involved in gliomas.
Tumor suppressor gene: A tumor suppressor gene normally restrains cell growth; its loss removes a key brake and contributes to glioma development.
Hypermutation / mismatch repair deficiency: Hypermutation is an unusually high number of mutations in a tumor, sometimes from a defect in DNA repair, which can affect treatment and may indicate an inherited condition.

Types & Subtypes

Astrocytoma, IDH-mutant, grade 2: An IDH-mutant grade 2 astrocytoma is a slower-growing diffuse glioma in younger adults, with a relatively favorable but watchful outlook.
Astrocytoma, IDH-mutant, grade 3: An IDH-mutant grade 3 astrocytoma is a more aggressive diffuse glioma than grade 2, generally treated with surgery, radiation, and chemotherapy.
Astrocytoma, IDH-mutant, grade 4: An IDH-mutant grade 4 astrocytoma is the most aggressive IDH-mutant astrocytoma, but generally has a better outlook than IDH-wildtype glioblastoma.
Oligodendroglioma, IDH-mutant and 1p/19q-codeleted (grade 2): A grade 2 oligodendroglioma is a slower-growing diffuse glioma defined by IDH mutation and 1p/19q codeletion, with the most favorable outlook among adult diffuse gliomas.
Oligodendroglioma, IDH-mutant and 1p/19q-codeleted (grade 3): A grade 3 oligodendroglioma is a more aggressive form of oligodendroglioma, still with a relatively favorable outlook and good response to chemotherapy.
Glioblastoma, IDH-wildtype: Glioblastoma, IDH-wildtype is the most common and aggressive adult glioma — a grade 4 tumor treated intensively but very difficult to cure.
"Molecular" glioblastoma: A "molecular" glioblastoma is an IDH-wildtype glioma diagnosed as glioblastoma based on molecular markers, even without the most aggressive appearance.
Gliosarcoma: Gliosarcoma is a variant of glioblastoma containing both glioma and sarcoma-like components, treated similarly to glioblastoma.
Giant cell glioblastoma: Giant cell glioblastoma is a rare variant of glioblastoma containing large, multinucleated tumor cells, treated like glioblastoma.
Epithelioid glioblastoma: Epithelioid glioblastoma is a rare glioblastoma variant, often carrying a BRAF V600E mutation that may open a targeted treatment option.
Diffuse midline glioma, H3 K27-altered: Diffuse midline glioma, H3 K27-altered is a serious grade 4 tumor of midline brain structures, occurring mainly in children, defined by an H3 alteration.
Diffuse intrinsic pontine glioma (DIPG): DIPG is a diffuse midline glioma of the brainstem's pons, one of the most serious childhood brain tumors, usually treated with radiation for symptom relief.
Diffuse hemispheric glioma, H3 G34-mutant: Diffuse hemispheric glioma, H3 G34-mutant is a high-grade tumor of the cerebral hemispheres in adolescents and young adults, defined by an H3 G34 mutation.
Pediatric-type diffuse high-grade glioma, H3- and IDH-wildtype: This is an aggressive childhood glioma lacking H3 and IDH mutations, defined by other molecular features and managed with multimodal treatment.
Infant-type hemispheric glioma: Infant-type hemispheric glioma is a glioma of very young children, often driven by targetable gene fusions, which can respond to targeted therapy.
Pilocytic astrocytoma: Pilocytic astrocytoma is a slow-growing, often curable grade 1 glioma — the most common brain tumor in children.
Pilomyxoid astrocytoma: Pilomyxoid astrocytoma is a variant related to pilocytic astrocytoma, occurring in young children and tending to behave somewhat more aggressively.
Pleomorphic xanthoastrocytoma (PXA): Pleomorphic xanthoastrocytoma is a usually lower-grade glioma of young people, often carrying a BRAF V600E mutation that may allow targeted therapy.
Subependymal giant cell astrocytoma (SEGA): SEGA is a benign-behaving tumor associated with tuberous sclerosis, often treatable with a targeted drug as well as surgery.
Angiocentric glioma: Angiocentric glioma is a rare, usually low-grade glioma of children and young adults that often causes seizures and is frequently cured by surgery.
Ganglioglioma: Ganglioglioma is a usually low-grade glioneuronal tumor that commonly causes seizures and is often cured by surgery.
Dysembryoplastic neuroepithelial tumor (DNET): A DNET is a benign-behaving glioneuronal tumor that typically causes seizures in young people and is generally cured by surgery.
Ependymoma (types): Ependymomas are gliomas of the ventricular lining, now classified by location and molecular features, with surgery central to treatment.
Myxopapillary ependymoma: Myxopapillary ependymoma is a distinct ependymoma of the lower spinal cord region, usually slow-growing and often treatable by complete removal.
Subependymoma: Subependymoma is a benign, slow-growing tumor of the ventricles, often found incidentally and requiring treatment only if it causes symptoms.
Optic pathway glioma: An optic pathway glioma is a usually low-grade glioma of the visual pathways, common in children with neurofibromatosis type 1, often managed without immediate surgery.
Tectal / focal brainstem glioma: A tectal or focal brainstem glioma is a usually low-grade, slow-growing brainstem tumor that is often managed conservatively, in contrast to DIPG.

Causes & Risk Factors

Idiopathic (unknown cause): For most gliomas, the cause is unknown (idiopathic) — they are not the result of anything the person did or could have prevented.
Sporadic (non-inherited) tumor: A sporadic glioma is one that occurs by chance, without an inherited cause — the situation for the great majority of gliomas.
Genetic predisposition syndromes (overview): Genetic predisposition syndromes are inherited conditions that raise the risk of gliomas (among other tumors), accounting for a small fraction of cases.
Neurofibromatosis type 1 (NF1): Neurofibromatosis type 1 is a genetic condition that raises the risk of gliomas, particularly optic pathway gliomas in children.
Neurofibromatosis type 2 (NF2): Neurofibromatosis type 2 is a genetic condition mainly associated with other nervous-system tumors, including ependymomas among gliomas.
Li-Fraumeni syndrome: Li-Fraumeni syndrome is an inherited condition (from a TP53 mutation) that raises the risk of several cancers, including gliomas.
Tuberous sclerosis complex: Tuberous sclerosis complex is a genetic condition associated with subependymal giant cell astrocytoma (SEGA), often treatable with a targeted drug.
Lynch syndrome / constitutional mismatch repair deficiency: These inherited conditions impair DNA repair, raising the risk of gliomas (among other cancers) and producing tumors with many mutations.
Turcot syndrome: Turcot syndrome is a term for the combination of brain tumors (including gliomas) with inherited intestinal polyp conditions.
Ionizing radiation exposure: Prior exposure to ionizing radiation, such as previous radiation therapy to the head, is the best-established environmental risk factor for gliomas.
Age (as a risk factor): Age affects glioma risk and type: gliomas can occur at any age, but specific types are more common in particular age groups.
Sex differences: Some gliomas occur somewhat more often in one sex than the other, though these differences are modest and do not change individual care.
Family history: A family history of glioma slightly raises risk in some cases, but most gliomas are not inherited, and a single affected relative usually does not indicate a syndrome.
Cell phones / electromagnetic fields (no proven link): Despite extensive study and public concern, cell phone use and electromagnetic fields have not been proven to cause gliomas.
Head injury (no proven link): Despite common belief, head injury has not been established as a cause of gliomas.
Diet and lifestyle (no proven link): No specific diet or lifestyle factor has been proven to cause gliomas, so they are generally not the result of personal choices.
Allergy / immune associations: Studies have observed that a history of allergies is associated with a somewhat lower glioma risk, an intriguing but not fully understood finding.
Germline versus somatic mutation: Germline mutations are inherited and present in all cells, while somatic mutations arise in the tumor itself; most glioma mutations are somatic.
Gliomagenesis (how gliomas develop): Gliomagenesis is the process by which a glioma develops, through the accumulation of genetic changes in glial or precursor cells.
Occupational / environmental exposures: Various occupational and environmental exposures have been studied as possible glioma causes, but none is firmly established apart from ionizing radiation.
Modifiable versus non-modifiable risk factors: Most glioma risk factors are non-modifiable (like age and genetics), and unlike some cancers, gliomas have few if any clearly modifiable risk factors.
Risk in children versus adults: Gliomas differ between children and adults in their types, biology, and risk factors, which is why pediatric and adult gliomas are classified separately.

Signs & Symptoms

Brain tumor headache: A brain tumor headache is a headache caused by a tumor, sometimes worse in the morning or with straining, though most headaches are not caused by tumors.
Raised intracranial pressure: Raised intracranial pressure is increased pressure inside the skull, which a glioma can cause, leading to headache, nausea, and other symptoms.
Seizure (tumor-related epilepsy): A seizure is a burst of abnormal electrical activity in the brain, a common symptom of gliomas — especially lower-grade ones — and often the first sign.
Focal seizure: A focal seizure arises from one area of the brain and causes localized symptoms that reflect the tumor's location.
Generalized seizure: A generalized seizure involves widespread brain activity, typically with loss of consciousness and convulsions, and can be a presenting sign of a glioma.
Focal neurological deficit: A focal neurological deficit is a loss of a specific brain function — such as weakness or speech difficulty — reflecting the location of a glioma.
Hemiparesis (weakness): Hemiparesis is weakness of one side of the body, which a glioma can cause by affecting the brain's motor areas or their pathways.
Sensory changes: Sensory changes are altered sensations — such as numbness or tingling — that a glioma can cause by affecting the brain's sensory areas.
Aphasia (language difficulty): Aphasia is difficulty with language — speaking, understanding, reading, or writing — caused by a glioma affecting the brain's language areas.
Dysarthria (speech difficulty): Dysarthria is difficulty with the physical production of speech — slurred or unclear speech — that a glioma can cause by affecting muscle control.
Visual disturbances / field loss: Visual disturbances or field loss are changes in vision that a glioma can cause by affecting the eyes' visual pathways in the brain.
Cognitive changes: Cognitive changes are problems with thinking, memory, attention, or processing that a glioma can cause, sometimes subtly.
Personality / behavioral changes: Personality or behavioral changes can result from a glioma, especially in the frontal lobes, and may be noticed first by family members.
Memory impairment: Memory impairment is difficulty forming or recalling memories, which a glioma can cause, particularly when it affects memory-related brain regions.
Nausea and vomiting: Nausea and vomiting can result from a glioma, often due to raised intracranial pressure, and may be worse in the morning.
Papilledema: Papilledema is swelling of the optic nerve seen on eye examination, a sign of raised intracranial pressure that a glioma can cause.
Balance and coordination problems: Balance and coordination problems can result from a glioma affecting the cerebellum or its connections, causing unsteadiness or clumsiness.
Dizziness / vertigo: Dizziness or vertigo can occur with gliomas, particularly those affecting the brainstem or cerebellum, though most dizziness has other causes.
Cranial nerve deficits: Cranial nerve deficits are problems with the nerves controlling the face, eyes, and other head functions, which a glioma — especially in the brainstem — can cause.
Swallowing difficulty (brainstem): Swallowing difficulty can result from a glioma affecting the brainstem, which controls swallowing, and requires careful management for safety.
Fatigue: Fatigue is profound tiredness that is common with gliomas and their treatment, and is more than ordinary tiredness.
Endocrine / hormonal effects (location-related): A glioma near hormone-regulating brain structures can disrupt hormones, causing effects such as fatigue, growth or developmental changes, or other symptoms.
Pediatric presentation (children): Gliomas in children can present differently than in adults, with symptoms that vary by age and that may be subtle or nonspecific.
Infant presentation (macrocephaly, etc.): In infants, a glioma may present with signs such as an enlarging head, bulging soft spot, vomiting, or developmental changes, since infants cannot describe symptoms.
Subacute onset: Many gliomas cause symptoms that develop gradually over weeks to months (subacute onset), which can delay recognition.
Incidental finding: An incidental finding is a glioma discovered by chance on imaging done for another reason, before it has caused noticeable symptoms.

Diagnosis & Imaging

Magnetic resonance imaging (MRI): MRI is the main imaging test for gliomas, using magnetic fields to produce detailed pictures of the brain without radiation.
Contrast enhancement (gadolinium): Contrast enhancement is the brightening of a tumor on MRI after a gadolinium injection, often indicating a more aggressive glioma or a leaky blood-brain barrier.
T1- and T2-weighted imaging: T1- and T2-weighted images are basic MRI sequences that show the brain differently, together helping reveal a glioma's location and characteristics.
FLAIR sequence: FLAIR is an MRI sequence that highlights tumor and swelling while suppressing normal fluid, helping show the full extent of a diffuse glioma.
Ring enhancement: Ring enhancement is a pattern on MRI where a tumor brightens in a ring around a darker center, often suggesting an aggressive glioma like glioblastoma.
Non-enhancing tumor: A non-enhancing tumor is a glioma that does not brighten with contrast on MRI, often (but not always) suggesting a lower-grade tumor.
Perfusion MRI: Perfusion MRI measures blood flow within a tumor, helping assess how aggressive a glioma may be and distinguish tumor from treatment effects.
MR spectroscopy: MR spectroscopy analyzes the chemical makeup of a tumor on MRI, providing clues to whether a lesion is a tumor and how aggressive it may be.
Diffusion-weighted imaging: Diffusion-weighted imaging measures the movement of water in tissue on MRI, helping assess tumor cellularity and distinguish gliomas from other conditions.
Diffusion tensor imaging / tractography: Diffusion tensor imaging maps the brain's nerve fiber pathways, helping surgeons plan around critical connections near a glioma.
Functional MRI (fMRI): Functional MRI maps which brain areas perform critical functions, helping surgeons plan to protect those areas near a glioma.
Computed tomography (CT): CT is a fast X-ray-based scan that can detect brain tumors and is especially useful in emergencies and for showing bone, calcium, or bleeding.
Positron emission tomography (PET): PET imaging uses a radioactive tracer to show tumor metabolism, helping assess gliomas and distinguish tumor from treatment effects.
Biopsy: A biopsy is the removal of a tumor tissue sample for examination, which is essential to diagnose a glioma's exact type and molecular features.
Stereotactic biopsy: A stereotactic biopsy is a precise, minimally invasive way to sample a glioma using image guidance, used when the tumor is deep or hard to reach.
Open biopsy / resection for diagnosis: An open biopsy or resection obtains tumor tissue during surgery, often combining diagnosis with removal of the tumor in one operation.
Molecular / genetic testing: Molecular testing analyzes a glioma's genetic and molecular features, which is now essential for accurate diagnosis and treatment selection.
Frozen section (intraoperative): A frozen section is a rapid examination of tumor tissue during surgery, giving the surgeon preliminary information to guide the operation.
Tumor board (multidisciplinary review): A tumor board is a meeting of specialists who jointly review a glioma case to recommend the best, coordinated treatment plan.
Differential diagnosis: A differential diagnosis is the list of possible conditions a finding might represent, which doctors narrow down to reach the correct glioma diagnosis.
Pseudoprogression: Pseudoprogression is a treatment-related change on imaging that mimics tumor growth but is not true progression, often occurring after chemoradiation.
Pseudoresponse: Pseudoresponse is an apparent improvement on imaging from certain drugs (like bevacizumab) that reflects reduced enhancement rather than true tumor shrinkage.
RANO criteria (response assessment): RANO criteria are standardized guidelines for assessing how a glioma responds to treatment on imaging, accounting for treatment-related effects.
Liquid biopsy (emerging): A liquid biopsy is an emerging blood- or fluid-based test that detects tumor-derived material, being studied as a less invasive way to assess gliomas.
Surveillance / follow-up imaging: Surveillance imaging is the regular MRI monitoring of a glioma over time, to detect any change, recurrence, or progression and guide ongoing care.

Treatment: Surgery

Maximal safe resection: Maximal safe resection is the surgical goal of removing as much tumor as possible while preserving neurological function.
Gross total resection: Gross total resection is the removal of all of the tumor that is visible on imaging and to the surgeon, associated with better outcomes for many gliomas.
Subtotal resection: Subtotal resection is the removal of part but not all of the visible tumor, often done when complete removal would be unsafe.
Extent of resection (prognostic): Extent of resection is how much of a glioma is removed surgically, which is an important factor affecting outcomes for many tumor types.
Biopsy-only (unresectable tumor): A biopsy-only approach obtains tissue for diagnosis without removing the tumor, used when a glioma cannot be safely resected.
Craniotomy: A craniotomy is the surgical opening of the skull to access and operate on the brain, the standard approach for removing many gliomas.
Awake craniotomy: An awake craniotomy is brain surgery performed while the patient is awake for part of it, allowing real-time testing to protect critical functions.
Intraoperative brain mapping: Intraoperative brain mapping identifies critical functional areas during surgery, guiding the surgeon to remove tumor while protecting those areas.
Eloquent brain (functional areas): "Eloquent" brain refers to areas that control critical functions, where surgery must be especially careful to avoid causing deficits.
Neuronavigation: Neuronavigation is an image-guided "GPS" for the brain that helps surgeons locate a glioma precisely and plan a safe approach.
Intraoperative MRI: Intraoperative MRI is the use of MRI during surgery to check in real time how much tumor remains, helping maximize safe removal.
Fluorescence-guided surgery (5-ALA): Fluorescence-guided surgery uses a substance (5-ALA) that makes tumor tissue glow, helping the surgeon see and remove high-grade glioma more completely.
Intraoperative neuromonitoring: Intraoperative neuromonitoring continuously tracks nervous-system function during surgery, alerting the team to protect critical functions in real time.
Supratotal resection: Supratotal (supramaximal) resection removes the tumor plus a margin of surrounding brain, an approach studied for select gliomas to improve outcomes.
Debulking / cytoreduction: Debulking is the surgical removal of as much tumor as possible to reduce its bulk, relieving symptoms and pressure even when complete removal is not possible.
Laser interstitial thermal therapy (LITT): LITT is a minimally invasive technique that uses laser heat, guided by MRI, to destroy a tumor through a small opening, useful for deep or hard-to-reach gliomas.
Tumor location and resectability: Tumor location is a major factor in whether a glioma can be safely removed, since tumors in critical or deep areas are harder to resect.
Surgical risks and complications: Brain tumor surgery carries risks — such as neurological deficits, bleeding, or infection — that the team works to minimize and weigh against the benefits.
Shunt / CSF diversion (tumor-related hydrocephalus): A shunt or CSF diversion relieves fluid buildup (hydrocephalus) caused when a glioma blocks the flow of cerebrospinal fluid.
Postoperative recovery: Postoperative recovery is the healing and rehabilitation period after glioma surgery, which varies by the individual and the operation.
Repeat surgery (at recurrence): Repeat surgery is a second operation when a glioma recurs or progresses, considered in select situations to remove regrowth.
Biopsy versus resection decision: The choice between biopsy alone and tumor removal depends on whether a glioma can be safely resected and the goals of treatment.

Treatment: Radiation, Chemo & Targeted

Radiation therapy (radiotherapy): Radiation therapy uses high-energy beams to damage and kill tumor cells, a cornerstone of treatment for many gliomas.
External beam radiation therapy: External beam radiation therapy delivers radiation from a machine outside the body, the most common way radiation is given for gliomas.
Fractionation: Fractionation is the practice of dividing the total radiation dose into multiple smaller treatments, which improves safety and effectiveness.
Standard fractionated radiotherapy: Standard fractionated radiotherapy delivers radiation in many small daily doses over several weeks, the typical approach for high-grade gliomas.
Hypofractionated radiotherapy: Hypofractionated radiotherapy delivers radiation in fewer, larger doses over a shorter time, often preferred for older or frailer patients.
Intensity-modulated radiation therapy (IMRT): IMRT is an advanced radiation technique that shapes the radiation beams precisely to the tumor, reducing the dose to surrounding healthy tissue.
Proton beam therapy: Proton beam therapy uses protons instead of X-rays to deliver radiation that stops at the tumor, reducing dose to surrounding tissue, especially valuable in children.
Stereotactic radiosurgery: Stereotactic radiosurgery delivers a precise, high dose of radiation to a small target in few sessions, used for select small or recurrent gliomas.
Chemotherapy (overview): Chemotherapy uses drugs to kill or slow the growth of tumor cells, an important part of treatment for many gliomas.
Temozolomide (TMZ): Temozolomide is the most commonly used chemotherapy drug for gliomas, taken as a pill and central to treating glioblastoma.
Stupp protocol (chemoradiation): The Stupp protocol is the standard treatment for glioblastoma, combining radiation with temozolomide followed by additional temozolomide cycles.
Adjuvant chemotherapy: Adjuvant chemotherapy is chemotherapy given after primary treatment (like surgery and radiation) to target remaining tumor cells.
PCV chemotherapy: PCV is a combination chemotherapy regimen used particularly for oligodendrogliomas and some other gliomas, often after radiation.
Lomustine (CCNU): Lomustine is a chemotherapy drug used for some gliomas, especially at recurrence, taken as a pill that can reach the brain.
Carmustine wafers (Gliadel): Carmustine wafers are dissolvable chemotherapy implants placed in the tumor cavity during surgery to deliver drug directly to the area.
MGMT-guided treatment: MGMT-guided treatment uses a tumor's MGMT status to help decide whether and how to use temozolomide, particularly in older patients.
Tumor treating fields (Optune): Tumor treating fields use electrical fields delivered through scalp patches to slow glioblastoma growth, added to standard treatment.
Bevacizumab (anti-VEGF): Bevacizumab is a drug that targets tumor blood vessel growth, used mainly to control swelling and symptoms in recurrent glioblastoma.
IDH inhibitors (vorasidenib, ivosidenib): IDH inhibitors are targeted drugs that block the mutant IDH enzyme; vorasidenib is approved for certain grade 2 IDH-mutant gliomas after surgery.
BRAF/MEK inhibitors: BRAF and MEK inhibitors are targeted drugs for gliomas with BRAF pathway changes, particularly effective in certain pediatric low-grade gliomas.
Targeted therapy (overview): Targeted therapy uses drugs aimed at specific molecular changes in a tumor, offering precise treatment when actionable changes are found.
Immunotherapy (in glioma): Immunotherapy aims to harness the immune system against tumors; in gliomas it is an active research area but not yet a standard treatment for most.
Clinical trials: Clinical trials are research studies testing new glioma treatments, offering access to emerging therapies and advancing care for future patients.
Corticosteroids and supportive medications: Corticosteroids reduce brain swelling around a glioma, relieving symptoms, and other supportive medications manage seizures, nausea, and more.

Prognosis & Outcomes

Prognosis (overview): Prognosis is the likely course and outcome of a glioma, which varies enormously by tumor type, grade, molecular features, and individual factors.
Prognostic factor: A prognostic factor is a feature that influences the likely outcome of a glioma, such as tumor grade, IDH status, age, or extent of resection.
Predictive factor: A predictive factor is a feature that indicates how well a glioma is likely to respond to a specific treatment, such as MGMT status for temozolomide.
Median survival: Median survival is the time at which half of a group of patients are still living, a population statistic that does not predict any individual's outcome.
Overall survival: Overall survival is the length of time patients live after diagnosis or treatment, a key outcome measure reported for groups of patients.
Progression-free survival: Progression-free survival is the time during which a glioma does not grow or worsen after treatment, a measure of how long a treatment controls the tumor.
Five-year survival rate: A five-year survival rate is the percentage of patients still living five years after diagnosis, a population statistic that varies widely by glioma type.
Tumor progression: Tumor progression is the growth or worsening of a glioma over time, which prompts reassessment and often a change in treatment.
Recurrence: Recurrence is the return or regrowth of a glioma after treatment, common in diffuse gliomas, which prompts consideration of further treatment options.
Malignant transformation: Malignant transformation is when a lower-grade glioma evolves into a higher-grade, more aggressive tumor over time, an important reason for ongoing monitoring.
IDH status (prognostic value): IDH status is one of the strongest prognostic factors in adult diffuse gliomas, with IDH-mutant tumors generally having a substantially better outlook.
MGMT status (predictive value): MGMT methylation status predicts how well glioblastoma responds to temozolomide and also carries prognostic significance.
Performance status (Karnofsky): Performance status, often measured by the Karnofsky scale, describes how well a person can carry out daily activities and is an important prognostic factor.
Age and prognosis: Age is an important prognostic factor in gliomas, with younger age generally associated with a better outlook, though it is one factor among many.
Extent of resection and outcome: The extent of surgical removal is an important factor in glioma outcomes, with more complete removal often associated with better results.
Grade and prognosis: Tumor grade is a major determinant of glioma prognosis, with lower-grade tumors generally having a better outlook than higher-grade ones.
Glioblastoma prognosis: Glioblastoma has a serious prognosis and is difficult to cure, though outcomes vary by individual factors and research continues to seek improvements.
IDH-mutant glioma prognosis: IDH-mutant gliomas generally have a more favorable prognosis than IDH-wildtype tumors, though they remain serious and require long-term care.
Oligodendroglioma prognosis: Oligodendrogliomas generally have the most favorable prognosis among adult diffuse gliomas, with good response to chemotherapy.
Pediatric low-grade glioma prognosis: Pediatric low-grade gliomas generally have a favorable prognosis, with many children doing well long-term, especially when the tumor can be removed.
Diffuse midline glioma prognosis: Diffuse midline glioma, including DIPG, has a grave prognosis, and care focuses on meaningful time, symptom relief, and compassionate support alongside research.
Quality of life and survivorship: Quality of life and survivorship focus on living as well as possible with a glioma — addressing function, well-being, and support throughout the journey.

Care Team, Support & Living With Glioma

Neuro-oncologist: A neuro-oncologist is a doctor specializing in the medical treatment of brain tumors, often coordinating a person's overall glioma care.
Neurosurgeon: A neurosurgeon is a surgeon specializing in operating on the brain and nervous system, who performs biopsies and tumor removal for gliomas.
Radiation oncologist: A radiation oncologist is a doctor specializing in treating tumors with radiation, who plans and oversees radiation therapy for gliomas.
Neuropathologist: A neuropathologist is a doctor who examines tumor tissue to diagnose gliomas, integrating microscopic and molecular features into the final diagnosis.
Neuroradiologist: A neuroradiologist is a doctor who specializes in interpreting brain imaging, helping detect, characterize, and monitor gliomas.
Medical oncologist: A medical oncologist is a doctor who treats cancer with medications and may be involved in glioma care, especially where a neuro-oncologist is not available.
Pediatric neuro-oncologist: A pediatric neuro-oncologist is a doctor specializing in brain tumors in children, providing expertise tailored to the unique needs of young patients.
Multidisciplinary care: Multidisciplinary care brings together specialists from different fields to plan and provide coordinated glioma treatment, improving the quality of care.
Oncology nurse / nurse navigator: An oncology nurse or nurse navigator provides hands-on care, education, and guidance, helping patients and families navigate the glioma journey.
Rehabilitation therapy (PT/OT/speech): Rehabilitation therapy — physical, occupational, and speech therapy — helps people regain or maintain function affected by a glioma or its treatment.
Neuropsychologist: A neuropsychologist assesses and helps with thinking, memory, and behavior affected by a glioma, guiding strategies and support for cognitive changes.
Palliative care: Palliative care focuses on relieving symptoms and improving quality of life at any stage of a glioma, alongside other treatments.
Social worker / care coordination: A social worker helps patients and families with the practical, emotional, and resource needs of facing a glioma, and supports care coordination.
Mental health support: Mental health support helps patients and families cope with the emotional impact of a glioma, through counseling, therapy, and other resources.
Symptom monitoring / when to seek care: Symptom monitoring means watching for new or worsening symptoms and knowing when to seek prompt medical care during a glioma journey.
Seizure management and safety: Seizure management and safety involve controlling tumor-related seizures with medication and taking precautions to stay safe, such as driving restrictions.
Survivorship care: Survivorship care addresses the ongoing needs of people living with or beyond a glioma, including monitoring, managing late effects, and supporting well-being.
Caregiver support: Caregiver support helps the family members and friends caring for someone with a glioma, addressing their own needs and well-being.
Clinical trial navigation: Clinical trial navigation helps patients find and access clinical trials that may be suitable for their glioma, opening additional treatment options.
Brain tumor support organizations: Brain tumor support organizations provide information, support, and resources for patients and families affected by gliomas.
Patient advocacy and community resources: Patient advocacy and community resources help patients access support, information, and assistance, and give voice to the needs of those affected by gliomas.
Financial and practical support: Financial and practical support helps patients and families manage the costs and logistical challenges of glioma care.
Shared decision-making: Shared decision-making is a collaborative process in which patients and their care team make treatment decisions together, based on evidence and the person's values.

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