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Brain Tumor Facts

A brain tumor is a mass or growth of abnormal cells in your brain or close to your brain.  


  • Nearly 78,000 new cases of primary brain tumors are expected to be diagnosed this year. This figure includes nearly 25,000 primary malignant and 53,000 non-malignant brain tumors.  
  • There are nearly 700,000 people in the U.S. living with a primary brain and central nervous system tumor. 
  • This year, nearly 17,000 people will lose their battle with a primary malignant and central nervous system brain tumor.
  • There are more than 100 histologically distinct types of primary brain and central nervous system tumors.
  • Survival after diagnosis with a primary brain tumor varies significantly by age, histology, molecular markers and tumor behavior.
  • The median age at diagnosis for all primary brain tumors is 59 years.

Types of Brain Tumors

Primary brain tumors can be benign or malignant 

  • Benign brain tumors do not contain cancer cells 
    • They can be removed, and they seldom grow back. 
    • Usually have an obvious border or edge. 
    • Cells rarely invade tissues around them. 
    • They don’t spread to other parts of the body. 
    • Can press on sensitive areas of the brain and cause serious health problems. 
    • Sometimes life threatening. 
    • May become malignant. 
  • Malignant brain tumors contain cancer cells 
    • They are generally more serious and often are a threat to life. 
    • They are likely to grow rapidly and crowd or invade the nearby healthy brain tissue. 
    • Cancer cells may break away from malignant brain tumors and spread to other parts of the brain or to the spinal cord. 
    • Doctors group brain tumors by grade. The grade of a tumor refers to the way the cells look under a microscope. Cells from low-grade tumors (grades I and II) look more normal and generally grow more slowly than cells from high-grade tumors (grades III and IV). Over time, a low-grade tumor may become a high grade tumor. 
    • Grade I: The tissue is benign. The cells look nearly like normal brain cells, and they grow slowly. 
    • Grade II: The tissue is malignant. The cells look less like normal cells than do the cells in a Grade I tumor. 
    • Grade III: The malignant tissue has cells that look very different from normal cells. The abnormal cells are actively growing (anaplastic). 
    • Grade IV: The malignant tissue has cells that look most abnormal and tend to grow quickly. 

The most common types are: 

  • Astrocytoma: The tumor arises from star-shaped glial cells called astrocytes. It can be any grade. In adults, an astrocytoma most often arises in the cerebrum. 
    • Grade I or II astrocytoma: It may be called a low-grade glioma.
    • Grade III astrocytoma: It’s sometimes called a high-grade or an anaplastic astrocytoma. 
    • Grade IV astrocytoma: It may be called a glioblastoma or malignant astrocytic glioma. 
  • Meningioma: The tumor arises in the meninges. It can be grade I, II, or III. It’s usually benign (grade I) and grows slowly. 
  • Oligodendroglioma: The tumor arises from cells that make the fatty substance that covers and protects nerves. It usually occurs in the cerebrum. It’s most common in middle-aged adults. It can be grade II or III. 
  • Acoustic neuromas (schwannomas): These are benign tumors that develop on the nerves that control balance and hearing leading from your inner ear to your brain. 
  • Pituitary adenomas: These are mostly benign tumors that develop in the pituitary gland at the base of the brain. These tumors can affect the pituitary hormones with effects throughout the body. 
  • Primitive neuroectodermal tumors (PNETs): These are rare, cancerous tumors that start in embryonic (fetal) cells in the brain. They can occur anywhere in the brain. 
  • Craniopharyngiomas: These rare, noncancerous tumors start near the brain's pituitary gland, which secretes hormones that control many body functions. As the craniopharyngioma slowly grows, it can affect the pituitary gland and other structures near the brain. 
Secondary (metastatic) brain tumors are tumors that result from cancer that starts elsewhere in your body and then spreads (metastasizes) to your brain. 
  • Most often occur in people who have a history of cancer. But in rare cases, a metastatic brain tumor may be the first sign of cancer that began elsewhere in your body.
  • More common than are primary brain tumors. 
  • Any cancer can spread to the brain, but the most common types include: 
    • Breast cancer 
    • Colon cancer 
    • Kidney cancer 
    • Lung cancer
    • Melanoma 
Brain Function
  • The three major parts of the brain control different activities: 
  • Cerebrum: The cerebrum uses information from our senses to tell us what is going on around us and tells our body how to respond. It controls reading, thinking, learning, speech, and emotions. The cerebrum is divided into the left and right cerebral hemispheres. The right hemisphere controls the muscles on the left side of the body. The left hemisphere controls the muscles on the right side of the body. 
  • Cerebellum: The cerebellum controls balance for walking and standing, and other complex actions. 
  • Brain stem: The brain stem connects the brain with the spinal cord. It controls breathing, body temperature, blood pressure, and other basic body functions.