Astrocytoma – Causes, Symptoms and Treatment

What is an Astrocytoma?

An astrocytoma is a tumor of the central nervous system that originates from abnormally transformed astrocytes – star-shaped glial cells that provide structural and metabolic support to neurons in the brain and spinal cord. Astrocytomas belong to the broader category of gliomas and represent one of the most common types of primary brain tumors. They can occur at any age but are particularly prevalent in children and young adults.

Classification and Grading

The World Health Organization (WHO) classifies astrocytomas into four grades based on their degree of malignancy:

• WHO Grade 1 (Pilocytic Astrocytoma): Slow-growing, well-circumscribed, and most common in children. Generally associated with a favorable prognosis.
• WHO Grade 2 (Diffuse Astrocytoma): Slow-growing but diffusely infiltrating; carries a risk of progression to higher-grade tumors over time.
• WHO Grade 3 (Anaplastic Astrocytoma): Faster-growing with increased cellular proliferation (mitotic activity) and a more aggressive clinical course.
• WHO Grade 4 (Glioblastoma): The most aggressive and most common malignant brain tumor in adults. Classified within the astrocytoma spectrum since the 2021 WHO update.

Causes and Risk Factors

The exact causes of astrocytoma development are not yet fully understood. Known and suspected risk factors include:

• Ionizing radiation: Prior radiation therapy to the head, especially during childhood, is a recognized risk factor.
• Genetic predisposition: Hereditary conditions such as Neurofibromatosis Type 1 and Li-Fraumeni syndrome are associated with an increased risk of astrocytoma.
• Molecular alterations: Mutations in genes such as IDH1 and IDH2 (isocitrate dehydrogenase) are strongly associated with lower-grade astrocytomas and have diagnostic and prognostic significance.

Common environmental factors such as mobile phone radiation are not considered established risk factors based on current scientific evidence.

Symptoms

The symptoms of an astrocytoma depend largely on the location, size, and growth rate of the tumor. Common symptoms include:

• Headaches, often worse in the morning or during physical exertion
• Epileptic seizures (frequently the first presenting symptom in low-grade astrocytomas)
• Nausea and vomiting caused by increased intracranial pressure
• Neurological deficits such as motor weakness, speech difficulties, or visual disturbances
• Changes in personality, mood, or cognitive function
• Dizziness and coordination problems

Diagnosis

Diagnosis of an astrocytoma involves a combination of neuroimaging and tissue analysis:

• MRI (Magnetic Resonance Imaging): The gold standard for visualizing the location, extent, and characteristics of the tumor.
• CT (Computed Tomography): Used as a complementary tool, particularly in emergency settings.
• Biopsy or surgical resection: Tissue sampling is essential for histological classification and molecular profiling.
• Molecular pathology: Testing for IDH mutations, ATRX loss, and 1p/19q codeletion is critical for accurate diagnosis, grading, and treatment planning.

Treatment

Treatment is individualized based on the WHO grade, tumor location, patient age, and overall health status. The main treatment modalities include:

Surgery

Surgical resection aims to remove as much of the tumor as safely possible while preserving neurological function. Maximal safe resection is the goal. In cases of complete removal of low-grade tumors, a watch-and-wait strategy may be appropriate.

Radiation Therapy

Radiotherapy is commonly administered after surgery, especially for higher-grade astrocytomas or when complete resection was not achievable. It targets residual tumor cells to reduce the risk of recurrence.

Chemotherapy

The alkylating agent temozolomide is the standard chemotherapy drug used for WHO Grade 3 and 4 astrocytomas, typically in combination with radiotherapy. PCV chemotherapy (procarbazine, CCNU, vincristine) is also used, particularly for IDH-mutant tumors.

Targeted Therapies and Clinical Trials

Newer approaches include targeted therapies directed at specific molecular alterations. For IDH-mutant astrocytomas, the IDH inhibitor vorasidenib has shown promising results in clinical trials. Participation in clinical studies is increasingly recommended for eligible patients.

Prognosis

Prognosis varies significantly by WHO grade and molecular profile. Low-grade astrocytomas (Grade 1–2) have a considerably better long-term outlook, especially following complete resection. Glioblastoma (Grade 4) carries a poor prognosis despite aggressive treatment, with a median survival of approximately 15 months. Regular MRI follow-up examinations are essential for all patients after treatment.

References

1. Louis DN et al. - The 2021 WHO Classification of Tumors of the Central Nervous System: a summary. Neuro-Oncology, 2021.
2. National Cancer Institute (NCI) - Adult Central Nervous System Tumors Treatment (PDQ). cancer.gov, 2024.
3. Stupp R et al. - Radiotherapy plus concomitant and adjuvant temozolomide for glioblastoma. New England Journal of Medicine, 2005; 352(10):987-996.