Causes and Risk Factors of Pilocytic Astrocytoma

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The underlying cause of pilocytic astrocytoma (PA), a rare tumor of the brain or spinal cord, is unknown. It most commonly occurs in children and young adults, and in people with genetic conditions such as neurofibromatosis, Li-Fraumeni syndrome, and tuberous sclerosis.

In this article, the causes and risk factors of PA will be explored.

Sample of DNA being pipetted into a petri dish over genetic results

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Common Risk Factors

A risk factor is something that is associated with the development of a disease like cancer but doesn't necessarily cause that disease. People who have a risk factor for developing PA won't necessarily develop one.

Some risk factors for PA include:

  • Age: PA is more common in children and young adults than older adults, though it can occur at any age.
  • Exposure to radiation: Therapeutic radiation (such as radiation therapy to the head for cancer treatment) is associated with a higher risk of developing a tumor in the brain over time. The average amount of time between radiation therapy for cancer and the subsequent development of secondary cancer is usually 10–15 years.
  • Prenatal Factors: Prenatal birth weight, specifically a high fetal growth rate, has been associated with an increased risk of PA. The reason for this finding isn't certain, but researchers think that conditions such as gestational diabetes (diabetes related to pregnancy) may play a role.

Genetics

Rarely, children have inherited abnormal genes from a parent that put them at increased risk for certain types of brain and spinal cord tumors like PA. In other cases, these abnormal genes are not inherited but occur as a result of changes (mutations) in the gene before birth.

People with inherited tumor syndromes often have tumors that start when they are young. Some of the better-known syndromes include:

  • Neurofibromatosis type 1: This is the most common syndrome linked to brain or spinal cord tumors. It is often inherited from a parent, but it can also start in some children whose parents don’t have it. Changes in the NF1 gene cause this disorder. PA occurs in about 15% of patients with neurofibromatosis type 1.
  • Neurofibromatosis type 2: This condition is less common than neurofibromatosis type 1. It can also either be inherited or may start in children without a family history. Changes in the NF2 gene are nearly always responsible for neurofibromatosis type 2.
  • Tuberous sclerosis: Also known as tuberous sclerosis complex, this is a rare genetic disease that causes benign (noncancerous) tumors to grow in various organ systems, including the brain, kidneys, heart, lungs, eyes, liver, pancreas, and skin. This condition is caused by changes in either the TSC1 or the TSC2 gene.
  • Li-Fraumeni syndrome: People with this syndrome have an increased risk of PA, as well as breast cancer, soft tissue sarcomas, leukemia, and some other types of cancer. It is caused by changes in the TP53 gene.
  • Turcot syndrome: Turcot syndrome is a rare condition characterized by the development of a brain tumor, with secondary tumors in the colon.

Lifestyle Risk Factors

Lifestyle-related risk factors such as diet, body weight, physical activity, and tobacco use play a major role in many adult cancers. But these factors usually take years to increase cancer risk, and they are not thought to play much of a role in childhood cancers, including brain tumors like PA.

At the current time, there is no known way to prevent or reduce the risk of pilocytic astrocytoma in your child.

Summary

Researchers are still studying the causes and risk factors associated with pilocytic astrocytoma but it is thought that certain genetic conditions can play a part. Previous radiation to the head from radiation therapy for cancer may have an effect.

A Word From Verywell

The majority of PA cases are spontaneous and not associated with any known risk factors. What's more, many of the known risk factors for PA cannot be prevented, such as inherited genetic conditions. There is a small risk of brain tumors in patients who have previously had radiation therapy to the head, and healthcare providers will take this into consideration before ordering radiation in children.

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3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Thierry-Chef I, Simon SL, Land CE, Miller DL. Radiation dose to the brain and subsequent risk of developing brain tumors in pediatric patients undergoing interventional neuroradiology proceduresRadiat Res. 2008;170(5):553–565. doi:10.1667/RR1393.1

  3. American Cancer Society. Risk Factors for Brain and Spinal Cord Tumors in Children. Revised June 2018.