Surgery is usually the first and often the only treatment needed for pilocytic astrocytoma, especially when the tumor can be completely removed. Pilocytic astrocytoma tumors usually stay in one area and don't grow into the healthy brain around them. They usually have clearly defined edges, which makes them easier to remove with surgery.
Sometimes pilocytic astrocytoma tumors grow in areas that are hard to reach, such as near the brainstem, optic nerves or hypothalamus. In these cases, removing the entire tumor could cause damage and affect important brain functions. When that happens, the healthcare team may suggest:
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Watching and waiting. If what's left of the tumor isn't growing or causing problems, you may need to have regular MRI scans to monitor it over time.
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Chemotherapy. Medicines that stop or slow tumor growth may be used to treat pilocytic astrocytoma. Children may have this treatment instead of radiation if possible.
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Targeted therapy. If testing shows a genetic change, such as a change in the BRAF gene, newer drugs can be used to block the tumor's growth signals.
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Radiation therapy. This may be used if other treatments don't work, especially in older people. It's used more carefully in children because it can cause long-term side effects. These can include memory problems, difficulty with attention or learning, and hormone changes that affect growth or puberty.
Even when surgery isn't possible or the tumor can't be fully removed, these other treatments often help manage symptoms, improve quality of life, and slow or stop tumor growth.
Potential future treatments
Some pilocytic astrocytomas have a genetic change in a gene called the BRAF gene. The BRAF gene helps control cell growth. When this gene is altered — especially in a form called BRAFV600E — it can cause tumors to grow. Newer drugs called BRAF or MEK inhibitors are designed to block this signal and may help slow or stop tumor growth.
Two of these drugs, dabrafenib (Tafinlar) and trametinib (Mekinist), are approved by the Food and Drug Administration (FDA) for children over age 1 with low-grade gliomas that have a BRAFV600E gene change. Pilocytic astrocytoma is one of the tumor types that may have this altered gene. These medicines are often used together as a combination therapy.
These medicines aren't usually the first treatment for pilocytic astrocytoma, but they may be considered when surgery isn't possible or if the tumor grows back.
As researchers continue to study how these tumors grow, targeted drugs may become a more common part of care in the future.
Prognosis and outcomes
The outlook, called prognosis, and survival rates for a pilocytic astrocytoma are usually very good, especially when the tumor can be completely removed with surgery. These tumors grow slowly and usually don't spread to other parts of the brain or body.
If the entire tumor is removed, most people don't need any more treatment and remain healthy for years. Sometimes the tumor can return or start growing again. This is called tumor recurrence.
Even when the tumor comes back, it often grows slowly. Other treatments such as chemotherapy, radiation therapy or targeted drugs may help keep it under control.
Age can affect the prognosis. Pilocytic astrocytoma is more common in children, and most children do very well after treatment. The prognosis in children is especially good when the tumor is in the cerebellum and can be completely removed.
In adults, pilocytic astrocytoma tumors are less common and may be harder to diagnose early. They also may behave differently. Sometimes these tumors may come back or be more difficult to treat. Adults also are less likely to show the genetic features that help guide targeted therapy.
Other factors that affect prognosis and outcomes can include:
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Tumor location. Tumors deep in the brain are harder to remove and more likely to come back.
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Age at diagnosis. Younger children may have a slightly higher risk of recurrence, even after surgery.
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Genetic makeup of the tumor. Tumors with certain gene changes, such as the BRAFV600E gene change or the KIAA1549-BRAF fusion (a gene change that causes continuous signals for cells to grow), may respond better to targeted therapies that block these signals.
Most people with pilocytic astrocytomas can live full, active lives with proper treatment and follow-up.