ON THIS PAGE: You will learn about how doctors describe the growth or spread of brain stem glioma. This is called the stage or grade. Use the menu to see other pages.
Staging is a way of describing where the tumor is located, if or where it has spread, and whether it is affecting other parts of the body. Doctors use diagnostic tests to find out the tumor's stage, so staging may not be complete until all of the tests are finished. Knowing the stage helps the doctor to decide what kind of treatment is best and can help predict a patient's prognosis, which is the chance of recovery. There are different stage descriptions for different types of tumors.
There is no formal staging system for childhood brain stem glioma. As explained in the Introduction, a brain stem glioma may be classified as either "diffuse" or "focal." In addition, the tumor may be classified by its grade.
Grade describes how much tumor cells look like healthy cells when viewed under a microscope. The doctor compares the tumor’s tissue with healthy tissue. Healthy tissue usually contains many different types of cells grouped together. If the tumor tissue looks similar to healthy tissue and contains different cell groupings, it is called differentiated or a low-grade tumor. If the tumor tissue looks very different from healthy tissue, it is called poorly differentiated or a high-grade tumor. The tumor’s grade may help the doctor predict how quickly it will spread. In general, the lower the tumor’s grade, the better the prognosis.
Below are the general classifications for brain stem glioma:
Diffuse brain stem glioma. This is the most common classification of brain stem glioma. This type of tumor spreads freely throughout the pons and often spreads to the midbrain, the medulla, or nearby parts of the brain. These tend to be high-grade tumors. They are very aggressive and contain abnormal-looking cells. If a biopsy was done, a diffuse brain stem glioma may be further classified by a specific genetic change in the tumor cells called H3 K27M.
Focal brain stem glioma. About 20% of brain stem tumors are focal, meaning they occur in 1 area or are contained within a small portion of the brain stem. They usually occur in the midbrain or medulla rather than the pons. These are usually benign or low-grade tumors. They are less aggressive and the tumor cells look more like healthy cells.
Recurrent brain stem glioma: Recurrent brain stem glioma is a tumor 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.
Information about the tumor’s grade 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.