Astrocytomas, what are they? – MAPFRE Blogs

Astrocytoma is a brain tumor of astrocytes. Learn about its types, symptoms, diagnosis and treatments such as surgery, radiotherapy and targeted therapies.

Astrocytoma is a tumor that originates in astrocytes, a type of glial cell (support and nutrition) of the central nervous system.

It is a subtype within gliomas that also includes oligodendrogliomas and ependymomas that originate from another type of glial cells, oligodendrocytes and ependymocytes respectively.

They are tumors that develop in the brain (more frequently) or in the spinal cord.

They can appear at any age, although some subtypes are more common in children and young people (pilocytic astrocytoma), and others in adults (high-grade diffuse astrocytoma).

Risk factors include having received previous cranial radiotherapy and certain hereditary syndromes (neurofibromatosis type 1, Li-Fraumeni syndrome or Turcot syndrome).

How are they classified?

In the classification of astrocytomas according to the 5th edition of the WHO (2021), tumors are classified based not only on the appearance of the tumor cells and the histological grade (the higher the grade, the more aggressive the tumor) but also based on the mutations that the tumor cells express.

Mutations are changes in the DNA sequence (deoxyribonucleic acid), which is the genetic material of cells. In astrocytomas, the IDH mutation is especially important.

Importance of the IDH mutation

“HDI” means isocitrate dehydrogenasean enzyme involved in cellular metabolism. The IDH mutation in astrocytomas occurs in the gene that encodes this protein and changes the normal function of this enzyme. The most common mutations in astrocytomas affect IDH1 (mainly) and, less frequently, IDH2.

It is a diagnostic marker since the most aggressive astrocytoma does not usually present this mutation, it is said to be wild IDH or “wild type” in English.

It is a prognostic marker since patients with mutated IDH live longer since IDH mutated tumor cells tend to grow more slowly and respond better to treatments.

It allows treatments to be personalized according to the molecular profile of the tumor with targeted therapies that inhibit the mutated enzyme or its effects on tumor metabolism.

Classification of astrocytomas

In summary, they are classified as:

Grade 1 Astrocytoma (Pilocytic)

• Slow growing, generally benign.
• More common in children and adolescents.
• It is usually surgically resectable and rarely progresses to a more aggressive tumor.

Diffuse astrocytoma, IDH-mutated (adult)

• Grades: 2.3 (anaplastic), 4.
• Characteristic mutations: IDH1 or IDH2 (better prognosis).
• IDH-wild astrocytoma.

Diffuse tumors that do not have IDH mutation (poor prognosis)

Equivalent: Many of these are classified as IDH-wild glioblastoma, grade 4.

When we say that a astrocytoma is diffuse, we mean that it presents an infiltrative growththat is, it does not grow in a localized manner, it is not well circumscribed, because the tumor cells spread between normal brain cells, which can represent a difficulty in achieving total surgical removal of the tumor.

What symptoms does it present?

The signs and symptoms of astrocytoma depend on the location of the tumor in the brain or spinal cord.

If it affects the brain it can cause:

• Seizureswhich can cause loss of consciousness.
• Headache which may be accompanied by nausea and vomiting.
• Changes in personality.
• Vision, speech or mobility problems.
• Very tired or very weak.

If it affects the spinal cord it can cause:

• Pain in the affected area.
• Progressive weakness in the arms or legs or problems walking.

Diagnosis

• Neurological examination: Abnormalities in the neurological examination can guide the location of the tumor.
• Radiological tests: MRI, positron emission tomography.
• Biopsy– A sample of tissue is removed from the tumor for analysis.

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Treatment

Usually includes:

• Surgery (when possible): performed by a Neurosurgery specialist. The main goals of surgery are: maximal safe resection of the tumor to delay progression and improve survival, relief of symptoms, and obtaining adequate tissue for pathologic diagnosis and grade determination. Sometimes, the location of the tumor makes it difficult to access or makes its removal very risky, so surgery must seek maximum resection without compromising safety.
• Radiotherapy: Radiation therapy uses beams of energy to destroy tumor cells. The energy can come from X-rays or protons and other sources. It is especially used if the surgical resection is incomplete or the tumor is high grade.
  • Standard fractionated external radiation therapy (EBRT): The most frequently used, it is administered in a limited area covering the tumor or surgical cavity and a small margin of adjacent brain tissue.
  • Hypofractionated radiotherapy: It is an appropriate option for selected patients (older adults and/or those with poor general condition). It is administered in fewer sessions with higher doses per session.
  • conformal radiotherapy (CRT), including 3D-CRT and IMRT (Intensity Modulated Radiotherapy): allows the tumor area to be precisely irradiated, protecting the surrounding healthy brain tissue. It is useful for astrocytomas in delicate locations or when focal irradiation is required.
  • Stereotactic radiation therapy (SRS or FSRT): Mainly used for small or recurrent tumors.
• Chemotherapy: used in high-grade tumors or as an adjuvant after surgery and radiotherapy to eliminate residual tumor cells.
  • Temozolomide: It is especially used in high-grade astrocytomas. It is used in combination with radiation therapy after surgery and as maintenance. If the tumor cells have the MGMT gene promoter methylated (it is a marker that is studied in the tumor) they are more sensitive to the drug. The presence of the IDH mutation has also been correlated with greater sensitivity to temozolomide.
  • PCV Scheme (procarbazine, lomustine and vincristine).
• Targeted therapy
  • Vorasidenib: It is not chemotherapy but a selective enzyme inhibitor of the mutant forms of the IDH1 and IDH2 enzymes. It has recently been approved in the United States (in 2024) and in Europe (2025) for the treatment of grade 2 gliomas, after surgery, that have susceptible mutations in IDH1 or IDH2.
• Clinical trials: Clinical trials are studies of new treatments. These studies present an opportunity to test the latest treatment alternatives.

What you should know…

• Astrocytoma is a type of brain tumor that originates in astrocytes and can affect people of any age, with different degrees of aggressiveness depending on its subtype.
• The IDH mutation is key to classifying, diagnosing and treating astrocytoma, since it influences the prognosis and allows targeted therapies to be applied.
• The treatment of astrocytoma combines surgery, radiotherapy, chemotherapy and specific therapies, depending on the grade of the tumor and its genetic characteristics.

Literature

• Louis, D.N., Perry, A., Wesseling, P., Brat, D.J., Cree, I.A., & Figarella-Branger, D. (2021). The 2021 WHO Classification of Tumors of the Central Nervous System: A Summary. Acta Neuropathologica, 142(6), 803–820. DOI: 10.1007/s00401-021-02357-1.
• NCCN guidelines version 2.2025 Central Nervous System Cancers.
• Blakeley J, Mohile NA, Messersmith H, Lassman AB, Schiff D; Therapy for Diffuse Astrocytic and Oligodendroglial Tumors in Adults Guideline Expert Panel. Therapy for Diffuse Astrocytic and Oligodendroglial Tumors in Adults: ASCO-SNO Guideline Rapid Recommendation Update. NeuroOncol. 2025 Jul 30;27(6):1412-1418. doi: 10.1093/neuonc/noaf072. PMID: 40304440; PMCID: PMC12309703.