Gastrointestinal Stromal Tumor - GIST: Stages

Approved by the Cancer.Net Editorial Board, 11/2022

ON THIS PAGE: You will learn about how doctors describe a tumor’s growth or spread. This is called the stage. Use the menu to see other pages.

What is tumor staging?

Staging is a way of describing where the tumor is located or if it has spread to another part of the body from where it started. If this happens, it is called metastasis. Doctors may also do tests to learn which treatments could work best.

Doctors use diagnostic tests to find out the tumor's stage, so staging may not be complete until all the tests are finished. Tests that may be used to find the stage include computed tomography (CT) scan, magnetic resonance imaging (MRI), or positron emission tomography (PET)-CT scan (see Diagnosis). Knowing the stage helps the doctor recommend the best kind of treatment, and it can help predict a patient's prognosis. There are different stage descriptions for different types of cancer.

For other types of gastrointestinal (GI) tumors, the most common staging tool used is called the TNM system. TNM is an abbreviation for tumor (T), node (N), and metastasis (M). However, the TNM system is not commonly used to stage a gastrointestinal stromal tumor (GIST). Instead, doctors look at different factors to determine a patient’s prognosis and the specific risk of how aggressive an individual tumor will be. Specifically, doctors want to figure out how quickly the GIST may grow and the chance the tumor will come back, or recur, after surgery.

For GISTs that have been removed and have not spread to other areas of the body, doctors commonly use the factors listed below to determine the risk of it coming back:

  • The size of the tumor

  • The mitotic count, which describes the number of dividing cells

  • The location where the tumor started

  • Whether the tumor ruptured and spilled into the abdomen (perforated)

A GIST that has spread to distant areas of the body is considered metastatic, or stage IV (4).

Information about the tumor’s stage 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.