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An astrocytoma is a type of brain tumor that begins in astrocytes—the small, star-shaped cells that form the brain’s connective tissues. Astrocytomas are the most common type of brain tumor among adults, with around 15,000 new cases diagnosed every year in the U.S.

Many cancers are classified by “stage,” which describes the tumor’s size, whether it has invaded surrounding tissues and if it has traveled to other areas of the body. Astrocytomas, however, are assigned “grades” according to the World Health Organization’s method of classifying brain tumors. This grading takes into account:

  • How abnormal the tumor cells appear under a microscope
  • How fast the tumor grows
  • The presence of newly developed blood vessels within the tumor

Grades range from 1 through 4, with 4 being the most aggressive. Here’s a closer look at astrocytoma grades and what they mean.

Grade 1 astrocytoma

A grade 1 astrocytoma is a slow-growing tumor that rarely expands into surrounding tissues. There are three types of grade 1 astrocytomas:

  • Pilocytic astrocytoma – Also known as juvenile pilocytic astrocytoma (JPA), this type of tumor mainly affects children and teens. It seldom grows into surrounding tissues and is usually considered cured after surgical removal.
  • Pleomorphic xantoastrocytoma – This type of tumor is often associated with seizures and tends to develop in the temporal lobes behind the ears. Surgery to remove the tumor is typically the only necessary treatment.
  • Subependymal giant cell astrocytoma (SEGA) – This rare type of tumor is most often seen in children, teens and young adults and is linked to a genetic syndrome called tuberous sclerosis. A SEGA is usually considered cured once the tumor is removed.

Grade 2 astrocytoma

A grade 2 (or "low-grade") astrocytoma is still a slow-growing tumor, but it’s more likely to invade surrounding tissues and become dangerous over time. Diffuse astrocytoma is one such brain tumor. As an invasive cancer, diffuse astrocytoma has no definite separation from healthy brain tissues and may require additional treatments such as radiation therapy or chemotherapy following surgical removal.

Grade 3 astrocytoma

A grade 3 astrocytoma grows faster than a grade 2 tumor. For example, anaplastic astrocytoma is a grade 3 tumor that has aggressive features such as a higher growth rate, more cellular abnormalities and more invasiveness than diffuse astrocytoma. Effectively treating this type of tumor requires surgical removal as well as a combination of radiation therapy and chemotherapy to destroy any remaining cancer cells. 

Grade 4 astrocytoma

A glioblastoma (GBM) is a grade 4 astrocytoma and the most common type of primary brain tumor. It’s highly aggressive and difficult to treat—a patient’s care plan may focus on minimizing symptoms and extending life. Glioblastoma treatment is currently a focus of many ambitious research initiatives and promising clinical trials.

Our approach to diagnosing and treating astrocytomas 

Florida's No. 1 cancer hospital and a high-volume cancer center, Moffitt Cancer Center the best option for brain tumor treatment. The multispecialty team within our Neuro-Oncology Program excels in diagnosing and treating all grades of astrocytomas and leads groundbreaking clinical trials to improve outcomes and quality of life for patients with aggressive tumors. Our relentless research efforts are evidenced by our designation as a Comprehensive Cancer Center by the National Cancer Institute.

For the best cancer outcomes, choose Moffitt first. Call our team today at 1-888-663-3488 or submit a new patient registration form online to schedule an appointment. A referral is not required to visit Moffitt.


Cancer Research UK: Astrocytoma and Glioblastoma
American Association of Neurological Surgeons: Astrocytoma Tumors