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A brain tumor is a growth of abnormal cells in the brain. Brain tumors are either benign (noncancerous) or are malignant (cancerous). Some types of tumors can spread through the spinal fluid and bloodstream to areas of the brain.

Brain tumors can develop in any part of the brain or skull including its protective lining, the underside of the brain (skull base), the brainstem, the sinuses and the nasal cavity, and many other areas. There are more than 120 different types of tumors that can develop in the brain. Brain tumors are dangerous because they can put pressure on healthy parts of the brain or spread into those areas.


  • Headaches
  • Seizures or convulsions
  • Difficulty thinking, speaking or finding words
  • Personality or behavior changes
  • Weakness, numbness or paralysis in one part or one side of the body
  • Loss of balance, dizziness or unsteadiness
  • Loss of hearing
  • Vision changes
  • Confusion and disorientation
  • Memory loss


The two main groups of brain tumors are primary and metastatic. Primary brain tumors are tumors that originate from the tissues of the brain or the brain's immediate surroundings and can be benign or malignant. Metastatic brain tumors are tumors that are located elsewhere in the body and migrate to the brain, usually through the bloodstream. Metastatic tumors are malignant.

Brain Tumor Grading

The grade of a brain tumor defines how serious it is. Brain tumor grading is a category system that describes the brain tumor cells and indicates how likely the tumor is to grow and spread.

The World Health Organization (WHO) has developed a grading system to determine a tumor's malignancy or benignity based on its structure under a microscope. Brain tumor grading uses a scale from 1 (least aggressive) to 4 (most aggressive).

Grade I brain tumor
  • Benign
  • Slow growing
  • Cells look almost normal under a microscope
  • Usually associated with long-term survival
  • Rare in adults
Grade II brain tumor
  • Relatively slow growing
  • Sometimes spreads to nearby normal tissue and comes back (recurs)
  • Cells look slightly abnormal under a microscope
  • Sometimes comes back as a higher-grade tumor
Grade III brain tumor
  • Malignant
  • Actively reproduces abnormal cells
  • Tumor spreads into nearby normal parts of the brain
  • Cells look abnormal under a microscope
  • Tends to come back as a higher-grade tumor
Grade IV brain tumor
  • Malignant
  • Most aggressive
  • Grows fast
  • Easily spreads into nearby normal parts of the brain
  • 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)


Sophisticated imaging techniques can pinpoint brain tumors. Diagnostic tools include computed tomography (CT or CAT scan) and magnetic resonance imaging (MRI). Magnetic resonance spectroscopy (MRS) is used to examine the tumor's chemical profile and determine the nature of the lesions seen on the MRI. Positron emission tomography (PET scan) can help detect recurring brain tumors.

Sometimes the only way to make a definitive diagnosis of a brain tumor is through a biopsy. A neurosurgeon performs the biopsy and a pathologist makes the final diagnosis, determining whether the tumor appears benign or malignant and grading it accordingly.


Brain tumor treatment options depend on the type of brain tumor and its size and location. The most common treatment for brain tumors is surgery. For some tumors, surgical removal and continued monitoring may be the only treatment needed. Chemotherapy and radiation therapy can be used to treat brain cancer by helping shrink the tumor, slowing down its growth and/or preventing it from coming back.

Locations Treating Brain Tumor