Understanding Brain Cancer: What Is Brain Cancer?

Understanding Your Brain

Before you can understand brain cancer, it’s helpful to understand how your brain works.

Your brain is basically a soft mass of tissue. It is protect by:

  • The bones in your skull.
  • Three thin layers of tissue called meninges.
  • Fluid that goes through spaces between the meninges and spaces in your brain. This is called cerebrospinal fluid.

Your brain controls the things you decide to do, like walking and talking. It also controls the things our body does naturally, like breathing. Your brain is in charge of your senses, memory, emotions and personality.

Here’s how your brain works. A network of nerves carries messages from your brain to the rest of your body. Other nerves travel through your spinal cord to connect your brain with other parts of your body.

There are 3 parts of your brain:

  • Cerebrum: takes information from our senses to tell our body how to respond. This part of your brain controls reading, thinking, learning, speech and emotions.
  • Cerebellum: controls your balance. This part of your brain controls walking, standing and other complex actions.
  • Brain stem: connects your brain with your spinal cord. The brain stem controls your breathing, body temperature, blood pressure and other body functions.

About Brain Cancer

A brain tumor occurs when abnormal cells develop in the tissues of your brain. According ot the National Cancer Institute (NCI), there were about 23,770 new cases of brain cancer in the U.S. in 2016.

Primary brain tumors are tumors that start in the brain. Cancer that spreads to your brain from another part of your body is not primary brain cancer. Lung cancer, breast cancer, kidney cancer, melanoma and other types of cancer commonly spread to the brain. When this happens, the tumors are called metastatic tumors. The cancer is named for the place it started. For instance, if the cancer cells in your lungs travel to your brain it is called metastatic lung cancer. It is not brain cancer.

In this article, we talk about only primary brain cancer. It’s important to note that not all brain tumors are malignant. Some are benign.

Benign vs. Malignant: What’s the Difference?

Benign means not cancerous. A benign tumor can get larger but does not spread to other tissues or organs. Malignant means cancerous. A malignant tumor’s cells can invade nearby tissue, lymph nodes and spread to other organs. These cells are destructive.

Benign brain tumors:

  • Can usually be removed.
  • Most often don’t grow back.
  • Have an obvious border or edge.
  • Are rarely fatal.
  • Don’t usually spread to tissues around them or other organs.
  • Can press on sensitive areas of the brain.
  • Can cause serious health problems.
  • Can become malignant.


Malignant tumors:

  • Can often be removed.
  • Are more serious.
  • Cancer cells can break away from malignant brain tumors and spread to other parts of the brain.
  • Are more likely to grow rapidly and invade nearby brain tissue.
  • Rarely spread to other body parts.
  • Can be fatal.

Most benign tumors in other parts of your body are not life threatening. Benign brain tumors are different, however. They might be serious.

What are the different types of brain tumors?

Types of Primary Brain Tumors

Primary brain tumors are named by:

  • The part of the brain where they start.
  • The type of cells they are.

Most brain tumors begin in glial cells. These are the cells that surround nerve cells and hold them in place. Tumors in the glial cells are called gliomas.

The most common types of brain tumors are:

Astrocytoma: The tumor occurs in the star-shaped glial cells called astrocytes. An astrocytoma can be any grade (severity). In adults, astrocytomas usually occur in the cerebrum. A more severe astrocytoma is called a glioblastoma or malignant astrocytic glioma.

Meningioma: The tumor occurs in the meninges. It can be any grade. A meningioma is usually benign and grows slowly.

Oligodendroglioma: The tumor occurs in cells that make up the fatty substance that covers and protects your nerves. Oligodendrogliomas usually grow in the cerebrum. It’s more common in middle-aged adults.

In children, the most common types of brain tumors are:

Medulloblastoma: This tumor usually occurs in the cerebellum. It is usually grade IV (more serious).

Astrocytoma: This is a low grade tumor that can occur anywhere in the brain. It’s usually grade I and less serious.

Ependymoma: This tumor occurs in cells that line the ventricles or central canal of the spinal cord. It can be any grade.

Brain stem glioma: This tumor occurs in the lowest part of the brain. It can be either low-grade or high-grade. 

Next: How is brain cancer diagnosed?

Back to “Understanding Brain Cancer: An Introduction”