Brain Tumor: Grades and Prognostic Factors

Approved by the Cancer.Net Editorial Board, 03/2019

ON THIS PAGE: You will learn about how doctors describe a brain tumor’s growth or spread. This is called the grade. You will also learn about the prognostic factors doctors use to help plan treatment. Use the menu to see other pages.

A staging system is used for most other types of tumors in other parts of the body, to describe where a tumor is located, if or where it has spread, and whether it is affecting other parts of the body. However, there is no recommended systemic staging system for adult brain tumors because most primary tumors do not usually spread beyond the central nervous system. The grading system described below is always used instead because the specific features of a brain tumor determine how cancerous it is and how likely it is to grow.

Prognostic factors

To decide on the best treatment for a brain tumor, both the type and grade of the tumor must be determined. There are several factors that help doctors determine the appropriate brain tumor treatment plan and a patient's prognosis:

  • Tumor histology. As outlined in the Diagnosis section, a sample of the tumor is removed for analysis. Tumor histology includes the type of tumor, the grade, and additional molecular features that predict how quickly the tumor can grow. Together, these factors will help your doctor understand how the tumor will behave. These factors may also help determine a patient’s treatment options.

    Grade describes certain features in the tumor that are linked with specific outcomes. For example, doctors may consider whether the tumor cells are growing out of control or if there are a lot of dead cells. Tumors with features generally linked with growing more quickly are given a higher grade. For most tumors, the lower the grade, the better the prognosis.

    Specifically for glial tumors, the grade is determined by its features, as seen under a microscope, according to the following criteria:

    • Grade I. These tumors are slow growing and unlikely to spread. They can often be cured with surgery.

    • Grade II. These tumors are less likely to grow and spread but are more likely to come back after treatment.

    • Grade III. These tumors are more likely to have rapidly dividing cells but no dead cells. They can grow quickly.

    • Grade IV. In a grade IV tumor, cells in the tumor are actively dividing. In addition, the tumor has blood vessel growth and areas of dead tissue. These tumors can grow and spread quickly.

  • Age. In adults, a person’s age and his or her level of functioning, called functional status (see below) when diagnosed is one of the best ways to predict a patient’s prognosis. In general, a younger adult has a better prognosis.

  • Symptoms. The symptoms a patient has and how long they last may also help determine prognosis. For example, seizures and having symptoms for a long time are linked with a better prognosis.

  • Extent of tumor residual. Resection is surgery to remove a tumor. Residual refers to how much of the tumor remains in the body after surgery. A patient’s prognosis is better when all of the tumor can be surgically removed. There are 4 classifications:

    • Gross total: The entire tumor was removed. However, microscopic cells may remain.

    • Subtotal: Large portions of the tumor were removed.

    • Partial: Only part of the tumor was removed.

    • Biopsy only: Only a small portion, used for a biopsy, was removed.

  • Tumor location. A tumor can form in any part of the brain. Some tumor locations cause more damage than others, and some tumors are harder to treat because of their location.

  • Molecular features. Certain genetic mutations found in the tumor may help determine prognosis. These include: IDH1, IDH2, MGMT, and a 1p/19q co-deletion. Sometimes, whether a tumor has these mutations determines the type of brain tumor that is diagnosed.

  • Functional neurologic status. The doctor will test how well a patient is able to function and carry out everyday activities by using a functional assessment scale, such as the Karnofsky Performance Scale (KPS), outlined below. A higher score indicates a better functional status. Typically, someone who is better able to walk and care for themselves has a better prognosis.

    • 100 Normal, no complaints, no evidence of disease

    • 90 Able to carry on normal activity; minor symptoms of disease

    • 80 Normal activity with effort; some symptoms of disease

    • 70 Cares for self; unable to carry on normal activity or active work

    • 60 Requires occasional assistance but is able to care for needs

    • 50 Requires considerable assistance and frequent medical care

    • 40 Disabled: requires special care and assistance

    • 30 Severely disabled; hospitalization is indicated, but death not imminent

    • 20 Very sick, hospitalization necessary; active treatment necessary

    • 10 Moribund, fatal processes progressing rapidly

  • Metastatic spread. A tumor that starts in the brain or spinal cord, if cancerous, rarely spreads to other parts of the body in adults, but may grow within the CNS. For that reason, with few exceptions, tests looking at the other organs of the body are typically not needed. A tumor that does spread to other parts of the brain or spinal cord is linked with a poorer prognosis.

  • Recurrent tumor. A recurrent tumor is one that has come back after treatment. If the tumor does return, there will be another round of tests to learn about the extent of the recurrence. These tests and scans are often similar to those done at the time of the original diagnosis.

Currently, the factors listed above are the best indicators of a patient’s prognosis. As discussed in Diagnosis, researchers are currently looking for biomarkers in the tumor tissue that could make a brain tumor easier to diagnose and allow for the staging of an adult brain tumor in the future. Researchers are also looking at other genetic tests that may predict a patient’s prognosis. These tools may someday help doctors predict the chance that a brain tumor will grow, develop more effective treatments, and more accurately predict prognosis.

Used with permission of the American College of Surgeons, Chicago, Illinois. The original and primary source for this information is the AJCC Cancer Staging Manual, Eighth Edition (2017) published by Springer International Publishing.

Information about the tumor’s grade, as well as the prognostic factors, will help the doctor recommend a specific treatment plan. The next section in this guide is Types of Treatment. Use the menu to choose a different section to read in this guide.