More than 120 types of primary brain tumors exist, making effective treatment perplexing. This includes malignant or benign tumors . Primary brain tumors are named according to the type of cells or by the part of the brain where it originates.

The glioma family of tumors results in 44.4 percent of all tumors with the glioblastoma being the most common type at 52 percent and the astrocytoma accounting for 21.6 percent of all gliomas. Individually, the meningioma is the most common type of brain tumor at 27.⁴ percent.¹

Secondary or metastatic brain tumors generate the greatest incidence rate. Breast, lung and melanoma are the most common cancers that spread to the brain.

Below are the common types of primary brain tumors:

Astrocytoma
Astrocytes , which can develop in any part of the brain or spinal cord, are star-shaped glial cells where the tumor originates. It can be any grade, but in adults, it most often arises in the cerebrum. Glioblastomas and astrocytomas combined represent 75 percent of all gliomas.¹ Commonly astrocytomas are classified in four grades:

• Grade I astrocytoma:
  • Called low-grade glioma
  • Slow growing
  • Well-defined borders
  • Rare and almost exclusively found in children or teens

• Grade II astrocytoma:
  • Rarely spreads to other parts of central nervous system
  • Slow growing
  • Borders not defined
  • Common among men and women, 20s to 50s

• Grade III astrocytoma:
  • Sometimes called a high-grade or an anaplastic astrocytoma
  • More aggressive than Grade II astrocytoma
  • Cells not uniform
  • Invades other tissue
  • More common in men than women

• Grade IV astrocytoma:
  • Called a glioblastoma or malignant astrocytic glioma
  • Most invasive type of glial tumor
  • Composed of several different cells, making it difficult to treat
  • Grows rapidly and invades other tissue
  • May have evolved from low-grade tumor
  • Common in young adults and among men and women, 50s to 70s
  • Account for 23 percent of all primary brain tumors²
  • More common in men

Astrocytoma, which account for 3,000 new cases a year in the U.S., is the most common form of brain cancer .³The annual U.S. incidence rate: three per 100,000.³

Meningioma
The tumor grows from the meninges , the layers of tissue covering the brain and spinal cord. As it grows, meningioma compresses other brain tissue which can affect cranial nerves. Sometimes the growth extends into facial bones, producing visible changes.

It is usually benign (Grade I) or low-grade. Still, the meningioma tumor can cause disability and be life-threatening. It also can be Grade II or III. Also:

• Cannot predict its rate of growth or how long it was growing prior to diagnosis
• Can arise after previous treatment from ionizing radiation or excessive X-ray exposure
• Grows slowly, which sometimes allows the brain to become accustomed to its presence
• Occurs at any age, but common among men and women, 40s to 50s
• Twice as common in women
• Can invade skull or metastasize to skin or lungs, although rare

Meningiomas represent about 30 percent of all primary brain tumors.¹ The annual U.S. incidence rate is: two per 100,000.³

Ependymoma
An ependymoma, part of the glial family (glial cells are the supportive cells of the brain), is a rare type of primary brain or spinal cord tumor. It originates in the ependyma, the cells that line the passageways in the brain where Cerebrospinal Fluid is produced. Also:

• Usually benign and local to an area of the brain, including the ventricles (cavities in the center of the brain)
• Can block the ventricles causing water on the brain
• Sometimes extends to spinal cord
• Can be slow or fast growing
• More than 90 percent occur in children, the third most common pediatric brain tumor

Ependymomas account for approximately three to six percent of central nervous system tumors4 and two percent of brain tumors.²

Oligodendroglioma
The tumor, usually occurring in the cerebrum, forms from cells that create the fatty substance that covers and protects nerves. The cerebrum, which is located in the anterior or front portion of the brain, determines personality, intelligence, sensory impulse and motor function. It can be Grade II or Grade III. Also:

• Frequently occurs in frontal or temporal lobes
• May be associated with chromosomal losses
• Average age of patient is 43, but can occur in children
• More common in men than women

Oligodendrogliomas account for approximately three percent of all brain tumors and five percent of all gliomas.¹The annual U.S. incidence rate: seven per 100,000.³

Medulloblastoma
The medulloblastoma is highly malignant (Grade IV) and usually originates in the cerebellum, the region of the brain that plays an important role in the integration of sensory perception, coordination and motor control. Also:

• Type of primitive neuroectodermal tumor, which is invasive and rapidly growing
• Unlike most brain tumors, spreads through the cerebrospinal fluid and frequently metastasizes to other locations in the brain and spine
• Most occur near brain stem
• May obstruct fourth ventricle, causing water on the brain
• Occurs most often in children under age 10, but can occur in adults
• Slightly more common in males than females

Medulloblastomas account for more than 25 percent of pediatric brain tumors.³ The annual U.S. incidence rate: two per 100,000.³

Brain stem glioma
Brain Stem Glioma are tumors located in the area of the brain called the brain stem, which connects the spinal cord with the brain and is located in the lowest portion of the brain, just above the back of the neck. It can be a low-grade or high-grade tumor, but the most common type is a diffuse intrinsic pontine glioma, which affects the pons portion of the brain stem and stymies nervous system functions. Also:

• Because of tumor location, it causes a challenge in treatment
• Account for 10 percent of pediatric brain tumors. The peak incidence is between ages 5 and 10⁵
• Can occur in adults
• Rarely spreads or metastasizes

Sources
¹Central Brain Tumor Registry of the United States (CBTRUS).
²National Brain Tumor Society.
³FreeMD.com.
⁴The Cern Foundation.
⁵St. Jude Children's Research Hospital.