Causes and Risk Factors of Anaplastic Astrocytoma

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The specific cause of anaplastic astrocytoma, a rare malignant brain tumor, is unknown. However, it is thought that certain genetic, environmental, and lifestyle factors are linked to its development.

This article will discuss these risk factors, as well as what decreases the risk of developing anaplastic astrocytoma and other kinds of brain tumors.

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Risk Factors

Scientists have identified a number of risk factors for developing brain tumors but have only clearly identified a few risk factors for anaplastic astrocytoma specifically.

In some cases, it is not clear the exact reason why certain risk factors increase the chance of developing this type of tumor.

Gender

Many epidemiological studies have reported a greater risk of anaplastic astrocytomas among men than women. According to these studies men are four times more likely to develop astrocytomas than women.

It has been proposed that this difference may be explained by the fact that women have a higher concentration of the hormone estrogen in their brains.

Some studies have also found that androgens, which are often referred to as the male hormones, increase the likelihood that tumor cells will spread from elsewhere in the body to the brain. Though both men and women have androgens, men have them in greater quantities.

Race

Studies have consistently found that non-Hispanic Whites have the highest number of cases of this type of brain tumor. In addition, there is a high rate of anaplastic astrocytoma in countries with large proportions of individuals of mostly European ancestry.

Racial Incidence

One study found that the incidence of glioma, which includes anaplastic astrocytoma, was 30% lower among Hispanic Whites, 52% lower among Blacks, 52% lower among Asians and Pacific Islanders, and 58% lower among American Indians and Alaska Natives than non-Hispanic Whites.

Non-Hispanic Whites often have greater and improved access to healthcare than other groups of people, which can lead to earlier and more accurate diagnoses. However, this is not thought to fully explain the large difference in incidence of anaplastic astrocytoma between non-Hispanic Whites and other ethnic groups.

Radiation Exposure

Exposure to moderate-to-high doses of ionizing radiation, such as in radiotherapy to the head and neck region during childhood to treat leukemia or a brain tumor, increases the risk of some brain tumors. These are more likely to be meningiomas rather than astrocytomas.

It is thought that the time between exposure to radiation and the development of anaplastic astrocytomas can be as great as 20–30 years. Getting a simple X-ray does not significantly increase your risk of developing a malignant brain tumor.

History of Allergies or Atopic Disease

Instead of increasing the risk of developing anaplastic astrocytomas, having allergies or atopic dermatitis, which includes allergic skin diseases such as eczema, are thought to decrease risk. It is not known why this is the case.

Genetics

There are a few rare, inherited disorders linked to an increased risk of anaplastic astrocytoma. They are:

  • Li-Fraumeni syndrome, which is a rare disorder that greatly increases the risk of developing several types of cancer, particularly in children and young adults
  • Neurofibromatosis type I, which is characterized by changes in skin color and the growth of tumors along nerves in the skin, brain, and other parts of the body
  • Tuberous sclerosis, a rare, multi-system genetic disease that causes benign (noncancerous) tumors to grow in the brain and on other vital organs, such as the kidneys, heart, eyes, lungs, and skin
  • Turcot syndrome, which is characterized by multiple colon polyps, an increased risk of colorectal cancer, and an increased risk of brain cancer

However, the majority of anaplastic astrocytoma cases are not inherited, meaning they do not pass from parents to children.

Scientists have discovered genetic mutations that they believe are linked to anaplastic astrocytoma. Having these genetic mutations means that someone is genetically predisposed to this type of brain cancer. However, that does not mean they will definitely develop anaplastic astrocytoma.

It is thought that the disease won't develop unless it is triggered by other factors, such as environmental or lifestyle factors.

Discuss Your Risk

If you have any concerns about an increased risk of developing anaplastic astrocytoma due to a close family member having one of the rare inherited diseases mentioned above, speak to your doctor. They will explain in greater detail what the risk to you is and refer you to genetic testing if they feel it is needed.

Lifestyle Risk Factors

Certain lifestyle risk factors may contribute to the development of specific types of cancer, including diet, smoking, and drinking alcohol.

Diet

Consuming high levels of processed meats has been linked to an increased risk of the group of brain cancers that anaplastic astrocytoma belongs to.

Processed meats include:

  • Cured meats, such as deli meats
  • Bacon
  • Hotdogs
  • Sausages
  • Lunchmeat

These types of meat are thought to be bad for you due to the processes that they go through when they are made.

Cured meats, such as salami, chorizo, and pepperoni, are the primary source of dietary N-nitroso compounds (NOCs). NOCs have long been associated with a higher risk of brain tumors.

Foods that are suggested to decrease the risk of brain tumors include:

  • Fish: A 2017 meta-analysis suggested that eating fish can lower your risk of brain tumors.
  • Vegetables, fruits, and vitamin A: The same 2017 meta-analysis also indicated that eating vegetables and fruits and taking vitamin A may reduce the risk of brain tumors.

Alcohol and Smoking

Both addictions to alcohol and smoking have been linked to higher rates of brain tumors. Among smokers, tobacco smoke is by far the greatest source of exposure to NOCs.

However, it is not clear whether there is a direct link between smoking and the development of this type of cancer.

Summary

The specific cause of anaplastic astrocytoma is unknown, but their occurrence is thought to be due to a combination of genetics, environmental factors, and lifestyle factors. Some cases of anaplastic astrocytoma may be hereditary, but the majority are not.

Men and non-Hispanic Whites are more prone to anaplastic astrocytoma than other people. Risk factors include exposure to moderate-to-high doses of radiation. Factors that are thought to reduce the likelihood of this type of tumor include a history of allergies and eating a diet with high amounts of fish and Vitamin A.

A Word From Verywell

Do bear in mind that, while a risk factor might be linked to an increased chance of developing anaplastic astrocytoma, you will not necessarily develop this type of tumor if you fall into this risk group. Anaplastic astrocytoma is rare, so your chances are slim for developing it.

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