Astrocytoma

What an astrocytoma is

Astrocytes are glial cells that support and nourish nerve cells. When they grow abnormally, they form a type of glioma. Astrocytomas can occur anywhere in the brain or spinal cord: in adults most often in the cerebral hemispheres, and in children often in the cerebellum, brainstem or optic pathway.

Doctors divide them into two broad groups:

• Circumscribed astrocytomas, such as pilocytic astrocytoma: well-defined, slow-growing, mostly in children and young adults.
• Diffuse astrocytomas: infiltrate surrounding brain, so they cannot be completely removed and tend to recur and progress.

Grades and classification

Since 2021, the World Health Organization classifies astrocytomas using both appearance and molecular markers:

The IDH mutation is a key prognostic marker. IDH-mutant tumors grow more slowly and respond better to treatment than IDH-wildtype tumors of similar appearance. Diffuse astrocytomas without IDH mutation and with certain molecular features are now classified as glioblastoma. Other markers (ATRX, CDKN2A, MGMT methylation, BRAF changes in pilocytic tumors) refine prognosis and treatment.

Symptoms

Symptoms come from pressure inside the skull and from the tumor's location:

• headaches, often worse in the morning or with coughing and straining, sometimes with nausea and vomiting
• seizures, the most common first sign of low-grade astrocytoma in adults
• personality or behavior change, poor concentration, memory problems (frontal and temporal lobes)
• weakness or numbness on one side
• speech or language difficulty (aphasia)
• vision problems (optic pathway, occipital lobe)
• balance and coordination problems (cerebellum, common in children)
• in spinal cord tumors: back pain, weakness, numbness, bladder problems

Low-grade tumors cause symptoms slowly over months or years; high-grade tumors over weeks.

Causes and risk factors

Most astrocytomas have no known cause. Known risk factors:

• previous radiation to the head
• genetic syndromes: neurofibromatosis type 1 (especially optic pathway gliomas), Li-Fraumeni syndrome, tuberous sclerosis

Mobile phones, head injuries and diet have not been proven to cause astrocytomas.

Diagnosis

1. Neurological exam of strength, sensation, reflexes, coordination, vision and thinking.
2. MRI with contrast: the main imaging test; advanced MRI techniques help plan surgery.
3. Biopsy or surgical removal: a pathologist confirms the tumor type, grade and molecular markers.
4. Spinal imaging in some cases, and eye examination for optic pathway tumors.

Treatment

Treatment is planned by a neuro-oncology team.

Surgery

The goal is to remove as much tumor as safely possible. Pilocytic astrocytomas can often be fully removed and cured. For diffuse tumors, maximal safe resection improves outcomes, sometimes using awake surgery and brain mapping to protect language and movement areas.

Radiation therapy

Used after surgery for grade 2 tumors with high-risk features, and for all grade 3 and 4 tumors. Proton therapy may be used in children to reduce effects on developing brain tissue.

Chemotherapy and targeted therapy

• Temozolomide or a combination called PCV, usually alongside or after radiation for higher-grade tumors
• Vorasidenib, an IDH inhibitor, approved in 2024 for some grade 2 IDH-mutant gliomas after surgery
• BRAF and MEK inhibitors for pediatric low-grade gliomas with BRAF changes

Supportive care

Anti-seizure medicines, steroids to reduce brain swelling, rehabilitation (physical, occupational and speech therapy), and psychological support.

Prognosis

Prognosis depends on grade, molecular markers, age, the extent of surgery and overall health:

• pilocytic astrocytoma: excellent; most children are long-term survivors after complete removal
• IDH-mutant grade 2: median survival often exceeds 10 years with modern treatment
• IDH-mutant grade 3 and 4: shorter, but better than IDH-wildtype glioblastoma

Low-grade tumors can transform into higher grades over time, so lifelong MRI follow-up is needed. See glioma and brain tumor for related information.

Frequently asked questions

Is an astrocytoma cancer?

Astrocytomas are primary brain tumors. Grade 1 tumors such as pilocytic astrocytoma behave benignly and are often cured with surgery. Diffuse astrocytomas (grades 2 to 4) are considered malignant because they infiltrate the brain and tend to progress, though they rarely spread outside the nervous system.

What are the first symptoms of an astrocytoma?

In adults, a seizure is often the first sign of a low-grade astrocytoma. Others include headaches that worsen over time, personality or memory changes, weakness, speech difficulty or vision problems. In children, headaches with vomiting and balance problems are common.

What is the difference between astrocytoma and glioblastoma?

Both arise from astrocytes. Glioblastoma is the most aggressive form, now defined mainly as IDH-wildtype grade 4 tumors. Astrocytomas with an IDH mutation, even at grade 4, generally grow more slowly and respond better to treatment.

What is the survival rate for astrocytoma?

It varies widely. Pilocytic astrocytomas in children have excellent long-term survival. Adults with IDH-mutant grade 2 astrocytoma often live more than 10 years. Higher grades have shorter survival. Your team can give an estimate based on the tumor's specific features.

Can an astrocytoma come back after surgery?

Diffuse astrocytomas usually recur because cells spread into surrounding brain beyond what surgery can remove. That is why radiation, chemotherapy and regular MRI scans follow surgery. Completely removed pilocytic astrocytomas rarely recur.