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Types of Tumors

There are many different types of brain tumors. They are usually classified by the type of cell the tumor grows from or the part of the brain where they are found.

Brain tumors may be benign (non-cancerous) or malignant (cancerous), depending on:

  • How they grow and change
  • If they come back after being removed

A benign (non-cancerous) tumor does not contain cancer cells. If it is removed with surgery, it usually does not recur (come back). Most benign brain tumors have clear borders. This means the tumor tissue does not spread to nearby healthy tissue.

Even though they aren't cancerous, benign tumors can cause symptoms by pressing on parts of the brain. Symptoms depend on the tumor's size and where it is located in the brain.

Malignant brain tumors contain cancer cells. They are usually fast growing and spread to nearby healthy tissue. Malignant brain tumors very rarely spread to other areas of the body, but may recur (come back) after treatment. Benign (non-cancerous) brain tumors are sometimes called malignant if they damage the brain because of their size or location.

Metastatic brain tumors are tumors that start in another part of the body. The tumor cells spread to the brain through the lymph system and bloodstream.

Cancers that commonly travel to the brain include:

  • Lung cancer
  • Breast cancer
  • Nasopharyngeal cancer
  • Melanoma (a type of skin cancer)
  • Colon cancer

Doctors describe and treat these cancers based on their specific type. For example, breast cancer that spreads to the brain is still called breast cancer.

Brain Tumor Grading System

Doctors use a grading system to indicate how benign or malignant a tumor is. This system is based on how the tumor cells look under a microscope.

The grading system developed by the World Health Organization (WHO) is:

Grade I tumor

  • Benign (non-cancerous)
  • Slow growing
  • Cells look almost normal under a microscope
  • Usually associated with long-term survival
  • Rare in adults

Grade II tumor

  • Relatively slow growing (slower than Grade III and IV)
  • Sometimes spreads to nearby normal tissue and recurs (comes back) after being removed
  • Cells look slightly abnormal under a microscope
  • Sometimes comes back as a higher grade tumor (cells are more abnormal when it comes back)

Grade III tumor

  • Malignant (cancerous)Actively reproduces abnormal cells
  • Tumor spreads into healthy brain tissue nearby
  • Cells look abnormal under a microscope
  • Tends to come back, often as a higher grade tumor (cells are more abnormal when it comes back)

Grade IV tumor

  • Most malignant (cancerous)
  • Grows fast
  • Easily spreads into healthy brain tissue nearby
  • Actively reproduces abnormal cells
  • Cells look very abnormal under a microscope
  • Tumor forms new blood vessels to maintain rapid growth
  • Tumors have areas of dead cells in their center (called necrosis)

How Common Are Brain Tumors?

If you or a family member or friend is diagnosed with a brain tumor, you might want to know how common brain tumors are. Doctors and scientists track this information in two ways:

  • Incidence (how many people are diagnosed with the disease in a certain time, such as a year)
  • Prevalence (how many people are living with the disease during a certain time)

The OHSU Brain Institute uses information from the Central Brain Tumor Registry of the United States (CBTRUS). This database tracks primary brain and central nervous system tumors (tumors that start in these areas), including:

  • All brain tumors, including benign (non-cancerous) and malignant (cancerous) tumors
  • All central nervous system tumors
  • Tumors of the pituitary and pineal glands
  • Tumors of the nasal cavity
  • Brain lymphoma and leukemia

Learn more about CBTRUS at http://www.cbtrus.org/    

Brain Tumor Incidence in Adults

The incidence of a disease is the number of new cases diagnosed in a certain time, such as a year. According to CBTRUS, about 62,930 new brain and central nervous system tumors were expected to be diagnosed in the United States in 2010. This includes benign (non-cancerous) and malignant (cancerous) tumors.

Brain Tumor Incidence in Children

According to CBTRUs, about 4,030 new brain and central nervous system tumors were expected to be diagnosed in children (age 0 to 19) in the United States in 2010. This includes benign (non-cancerous) and malignant (cancerous) tumors. Of these 4,030 new tumors, about 2,880 will be in children younger than 15.

Brain Tumor Prevalence in Adults

The prevalence of a disease is the number of people living with it during a certain time, such as a year. According to CBTRUS, about 290 in every 100,000 people were estimated to have primary brain and central nervous system tumors (tumors that start in the brain or central nervous system) in 2004.

For the total United States population, CBTRUS estimated that more than 612,000 people were living with primary brain or central nervous system tumors in 2004. Of these people, CBTRUS estimated that more than 124,000 people were living with malignant (cancerous) tumors and more than 488,000 people were living with benign (non-cancerous) tumors.

Brain Tumor Prevalence in Children

According to CBTRUS, about 35.4 children (age 0 to 19) were living with primary brain and central nervous system tumors (tumors that start in the brain or central nervous system) in 2004.For the total United States population, CBTRUS estimated that more than 28,000 children were living with primary brain or central nervous system tumors in 2004.

More facts and statistics from the American Brain Tumor Association