Brain Tumor - Grades and Prognostic Factors

Approved by the Cancer.Net Editorial Board, 06/2016

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. To see other pages, use the menu.

A staging system is used for most other types of cancer 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 how cancerous a tumor is and how likely it is to grow depends on its specific features.

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 determine 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. 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 specific 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. This is a separate group of tumors called juvenile pilocytic astrocytoma (JPA) and subependymoma. These are noninvasive and slow growing and can often be cured with surgery.

    • Grade II. These tumors do not have actively dividing cells or dead cells in the tumor, called necrosis, but show many abnormal cells. A grade II tumor can be an astrocytoma, ependymoma, or oligodendroglioma.

    • Grade III. These tumors are given a grade based on the cell type. For example, anaplastic astrocytoma is a grade III tumor that contains dividing cells but no dead cells. In contrast, anaplastic oligodendroglioma and anaplastic ependymoma are grade III tumors that do have dead cells.

    • Grade IV. A grade IV tumor is usually glioblastoma. Cells in the tumor are actively dividing. In addition, the tumor has blood vessel growth and areas of dead tissue.

  • Age of patient. In adults, the age of the patient 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.

  • 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.

  • 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

0   Dead

  • 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 Joint Committee on Cancer (AJCC), Chicago, Illinois. The original source for this material is the AJCC Cancer Staging Manual, Seventh Edition published by Springer-Verlag New York, www.cancerstaging.net.

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 Treatment Options. Or, use the menu to choose another section to continue reading this guide.