Astrocytoma

Astrocytomas are tumors that grow from astrocytes, star-shaped support cells of the brain and spinal cord. They are the most common brain tumors in children. Most childhood astrocytomas are low-grade and slow-growing.

Astrocytoma grading

• Grade 1 (e.g. pilocytic astrocytoma) — slow-growing and well-defined; often cured by surgery alone.
• Grade 2 (diffuse astrocytoma) — slow-growing but spreads into nearby brain tissue.
• Grade 3 (anaplastic astrocytoma) — fast-growing and malignant.
• Grade 4 (e.g. glioblastoma, diffuse midline glioma) — the most aggressive.

Biological features

Many pediatric low-grade astrocytomas carry changes in the BRAF gene (fusions or V600E mutation). Identifying these changes opens the way to targeted treatment.

Causes and risk factors

Usually no cause is found. Neurofibromatosis type 1 and tuberous sclerosis increase the risk, as does previous radiation to the head.

Symptoms

• Headaches, nausea and vomiting, often worse in the morning
• Problems with balance, walking or coordination
• Vision changes
• Seizures
• Weakness on one side of the body, or changes in behaviour or school performance

Imaging shows the tumor; surgery or biopsy confirms its type and grade.

Physical exam and case history

A full history of symptoms and their timing.

Neurological exam

Checks strength, sensation, reflexes, balance, coordination and mental status.

Visual field exam

Tests side (peripheral) vision, which tumors near the optic pathways can affect.

MRI with gadolinium

The most important scan; shows the exact size and position of the tumor.

CT scan

Used in emergencies or when MRI is not possible.

Biopsy

Tissue from surgery or a needle biopsy is examined to determine the type and grade.

Lumbar puncture

Occasionally used to look for tumor cells in the spinal fluid.

Molecular testing

Looks for BRAF, H3 K27M, IDH and other changes that guide treatment.

Treatment depends on the grade, location and molecular features of the tumor, and on the child's age.

Observation and close monitoring may be recommended when:

• The tumor is small, slow-growing and causing no symptoms
• The child has neurofibromatosis type 1 and the tumor is stable

Surgery

Complete removal of a low-grade astrocytoma is often curative.

Chemotherapy

Used for low-grade tumors that cannot be removed or continue to grow, especially in younger children, to delay or avoid radiation.

Targeted therapy

BRAF and MEK inhibitors (for example dabrafenib with trametinib, or tovorafenib) are highly effective for tumors with BRAF changes.

Radiation therapy

Used for high-grade tumors, and for low-grade tumors in older children that progress despite other treatment.

Bone marrow / stem cell transplant with high-dose chemotherapy

Considered in selected cases of high-grade or recurrent tumors within specialized protocols.

Holistic care

Rehabilitation, vision and hormone follow-up, schooling support and family counselling.

Our pediatric neuro-oncology team treats astrocytomas together with neurosurgeons and neuro-radiologists.