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Your Complete Guide to Primary Brain Tumors

Tumors that start growing in the brain are primary brain tumors and generally will not travel to other parts of the body. Tumors that start elsewhere in the body and spread to the brain are metastatic brain tumors.

Primary Brain Tumors

Primary brain tumors start in the brain. Typically, they are rated by a neuropathologist by the way they look under a microscope, using the World Health Organization (WHO) grading scale from I to IV (1 to 4):

  • Grade I (1): Slow-growing tumor cells; almost normal appearance; least aggressive; usually curable by surgery alone
  • Grade II (2): Relatively slow-growing cells; slightly abnormal appearance; can invade nearby tissue; may recur as a higher grade
  • Grade III (3): Actively growing cells; abnormal appearance; infiltrates normal tissue; also referred to as “anaplastic tumors”
  • Grade IV (4): Rapidly reproducing abnormal cells; very abnormal appearance; area of dead cells (necrosis) in center

The following are a list of primary brain tumors and their treatments:

  • High-grade gliomas (grades III and IV) grow from the cells that make up the brain. They are called astrocytoma (“astro”), oligodendroglioma (“oligo”), and glioblastoma (“GBM”), also known as grade IV astrocytoma. GBM is the most common type of adult primary brain tumor. The usual treatment after surgery is radiation and chemotherapy. Treatment in a clinical trial may also be offered.
  • Low-grade gliomas (grade II) include astrocytomas and oligodendrogliomas. Treatment after surgery may include radiation or chemotherapy. If these tumors are not growing rapidly or causing symptoms, sometimes they will just be observed without other treatment. Treatment in a clinical trial may also be offered.
  • Very low-grade gliomas (grade I) such as Juvenile pilocytic astrocytomas grow from cells that make up brain tissue. Surgery alone is generally the treatment but is sometimes followed by radiation and chemotherapy if complete resection is not achieved.
  • Ganglioglioma and gangliocytomas are tumors that come from cells or nerves that make up brain tissue. They are not very common and generally are grade 1 but rarely can be malignant. Treatment for low grade is surgery alone. For higher grade or an incomplete resection of a low grade may require radiation.
  • Meningiomas grow from the lining of the brain and are graded I, II, or III. Grade 1 Meningiomas are the most common type and is generally treated with surgery alone. Grade 2 are less common and are treated with surgery followed by radiation in most cases. Grade 3 are rare and are aggressive therefore radiation is recommended.
  • Schwannomas are tumors that come from the nerve cell, most commonly the vestibular nerve. The tumors are benign but can cause brainstem compression affecting hearing and potentially cause other conditions such as hydrocephalus. Treatment is surgery and or radiation therapy.
  • Subependymomas grow from the lining of the ventricles. Surgery alone is generally the treatment. These are very low grade tumors.
  • Ependymomas grow from the lining of the ventricles. Treatment of low grade Ependymoma tumors is surgery alone. Treatment for higher grade will likely involve radiation after surgery.
  • Hemangioblastomas are tumors that come from blood vessel cells. The most common location is cerebellum. They are generally benign tumors. Treatment is surgery possibly followed by radiation if the entire tumor is not removable.
  • Pineal tumors come from the pineal gland in the center of the brain. Pineal gland tumors are rare and several different types of tumors can arise from the pineal gland requiring different treatments.
  • Medulloblastomas are tumors that come from undeveloped cells in the cerebellum. These tumors are malignant but with correct treatment can be cured. These tumors are found in children.
  • Pituitary adenomas grow from the pituitary gland. Some, but not all, tumors secrete hormones. Treatment is usually surgery. If the tumor cannot be safely removed with surgery, or if the tumor grows back after surgery, radiation may be recommended. Other doctors who are experts with hormones will also be part of your care.
  • Craniopharyngiomas come from pituitary gland embryonic tissue. They are benign tumors. These tumors are more common in children but also affect adults. Treatment is surgery. Radiation is used sometimes if the entire tumor is not removed.
  • Primary central nervous system lymphoma grows from lymphocytes (a type of white blood cell) in the brain. These are typically treated with chemotherapy and possibly radiation therapy.

Metastatic Tumors

Metastatic tumors to the brain are tumors (cancers) that have spread from another part of the body. Metastatic tumors are the most common brain tumor. The most common cancers that spread to the brain are lung, breast, renal, melanoma, and colon cancer. These tumors are usually treated with surgery that is sometimes followed by radiation such as Gamma Knife or CyberKnife. In the case of a new cancer diagnosis, chemotherapy is prescribed to treat the primary tumor site. In the case of a known cancer diagnosis, it is important to follow up with your Oncologist after surgery.

The Author

Ivy Center

7 Replies to “Your Complete Guide to Primary Brain Tumors”

    • February 20, 2021


    • February 20, 2021


    2 Response
    1. Ivy Center
      • February 25, 2021

      Hello Rose, Please call 602-406-6489. Thank you!

    2. Blanca Rosa Aviles
      • April 3, 2021

      Hi I am currently taking care of my mother who they say has Terminal Brain Cancer. I wud like to ask you a couple of questions please. Thanks….Blanca Rosa A.

      1 Response
      1. Ivy Center
        • May 3, 2021

        Hi Blanca! We are very sorry to hear about your mother’s diagnosis. We would be happy to answer any questions you may have. Our team of experts will be a hosting a Live Q&A Roundtable on Clinical Trials Day, May 20, where we will be answering questions from the audience. Please feel free to submit a question and learn more about the event here: We also recommend you reach out to one of our Ivy Navigators at 602-406-8605 for any additional questions or resources you may need. Thank you!

  3. Eddye Morrison
    • February 22, 2021

    This article didn’t clarify what I’m looking for I am seeking out what the orange and red colors mean from a pet scan located in the brain

    1 Response
    1. Ivy Center
      • March 3, 2021

      Hi Eddye, great question! Pictures from a PET scan display bright spots from higher to lower as red > orange > yellow > green > blue where the radioactive tracer has collected. These spots reveal higher levels of chemical activity in red and lower in blue and this gives us details about how your tissues and organs are functioning and how metabolically active.

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