Pilocytic astrocytoma

What is pilocytic astrocytoma?

Pilocytic astrocytoma (PA) is the most common brain tumor in children. Because these tumors grow slowly and rarely spread, they are considered benign (noncancerous) and classified as stage 1 tumors. PAs most often occur in the cerebellum (the lower back part of the brain), in which case they may be referred to as cerebellar astrocytomas. But they also can develop anywhere in the central nervous system, including the brain stem, hypothalamus, optic nerve and spinal cord.

Astrocytomas develop in astrocytes, star-shaped cells that nourish the nervous system. The symptoms and recommended treatment for a pilocytic astrocytoma depend on the tumor's size and location. Complete tumor removal, when possible, can cure the condition.

However, if a PA gets too big, it can damage brain tissue. Children may then develop complications, such as brain stem compression or hydrocephalus (fluid buildup in the brain's cavities), both of which require immediate treatment.

Causes of pilocytic astrocytoma

In most cases, we don't know why children develop pilocytic astrocytomas, though some rare genetic conditions do increase a child's risk of PA. These conditions include neurofibromatosis type 1 (NF1), tuberous sclerosis complex, Turcot syndrome and Li-Fraumeni syndrome.

Symptoms of pilocytic astrocytoma

PA symptoms vary depending on the tumor's size and location.

Common symptoms include:

• Headaches
• Fatigue
• Nausea and vomiting
• Walking and balance difficulties
• Weight gain or loss
• Premature puberty

Some of these symptoms, such as headaches, fatigue and nausea, result from the growing tumor pressing on the brain or from the tumor blocking the flow of cerebrospinal fluid (the protective liquid surrounding the brain and spinal cord).

Other symptoms may be related to the affected part of the brain. For instance, a PA near the optic nerve may affect vision. A PA near the hypothalamus (a part of the brain involved in hormone production) may cause weight changes or premature puberty. A PA in the cerebellum can create issues with balance and coordination.

Diagnosis of pilocytic astrocytoma

If your child's symptoms suggest a tumor, their doctor will take a medical history and perform a neurological exam. But since testing is needed to make a diagnosis, your child may have one or more of the following:

• Magnetic resonance imaging (MRI) scan. This technique uses magnetic fields and radio waves to produce detailed images, which can clearly show a brain tumor's size, location and characteristics.
• Computed tomography (CT) scan. Using X-rays, this computerized technique delivers detailed cross-sectional images. A CT scan can help doctors determine a tumor's location and size.
• Biopsy. This involves taking a small sample of the tumor's cells to examine under a microscope. A biopsy may be performed during surgery to remove the tumor or in a separate procedure in which the surgeon makes a small hole in the skull and, guided by imaging, uses a hollow needle to withdraw a tiny piece of the tumor.

Treatment of pilocytic astrocytoma

Treatment options depend on the tumor's size and location and the child's overall health. Taking all relevant factors into account, we develop a personalized plan for each of our patients.

Surgery for pilocytic astrocytoma

The standard treatment for pilocytic astrocytoma is surgery. This type of tumor usually has well-defined boundaries, so if it's surgically accessible, a neurosurgeon may be able to remove it entirely. With complete removal, the chance of recurrence is low, though patients may still benefit from follow-up MRIs for a number of years. The 10-year survival rate for patients who had successful surgery is greater than 90%.

But not all PAs can be resolved through surgery alone. Tumors that arise in the hypothalamus or optic nerve tend to be intertwined with healthy brain tissue, making it difficult to fully remove them. In those cases, additional treatment may be needed.

Children with tumors causing hydrocephalus may need to undergo a procedure before the removal surgery in order to relieve built-up cerebrospinal fluid in the brain. For this procedure, the surgeon inserts a shunt (a plastic tube) that drains the excess fluid to the abdomen, where it can be absorbed back into the body. After the tumor is removed and the fluid is draining normally, the shunt is removed.

Chemotherapy for pilocytic astrocytoma

Chemotherapy is the administration of drugs that destroy or shrink cancer cells. It's used when a pilocytic astrocytoma can't be surgically removed or given after surgery to eliminate any remaining cancer cells. Chemo drugs may be given orally or intravenously (infused through a vein).

Radiation therapy for pilocytic astrocytoma

Radiation therapy may be used in older children with tumors that couldn't be completely removed by surgery. Radiation can shrink or kill cancer cells, but it's rarely used to treat young children because it can cause long-term problems with growth and development.

Investigational therapies for pilocytic astrocytoma

Patients may have opportunities to participate in clinical trials of promising treatments for pilocytic astrocytoma. Learn more about the process and potential benefits of enrolling your child in a clinical trial.