Oncologist-approved cancer information from the American Society of Clinical Oncology


Gastrointestinal Stromal Tumor - GIST

This section has been reviewed and approved by the Cancer.Net Editorial Board, 11/08

Staging

Staging


Staging is a way of describing a cancer, such as where it is located, whether it has spread, and if it is affecting the functions of other organs in the body. Doctors use diagnostic tests to determine the cancer's stage, so staging may not be complete until all 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 (chance of recovery). There are different stage descriptions for different types of cancers.

There is no standard staging system for GIST; however, the two most common factors in determining the risk of a GIST being cancerous are the size of the tumor and the mitotic count (the actual number of dividing cells). The following table was developed from the Gastrointestinal Stromal Tumor (GIST) Workshop:

Proposed Approach for Defining Risk of Aggressive Behavior in GISTs
  Size of Tumor* Mitotic Count
Very low risk Smaller than 2 cm Less than 5/50 HPF
Low risk 2 cm to 5 cm Less than 5/50 HPF
Intermediate risk Larger than 5 cm 6 to 10/50 HPF
  5 cm to 10 cm Less than 5/50 HPF
High risk More than 5 cm More than 5/50 HPF
  More than 10 cm Any mitotic rate
  Any size More than 10/50 HPF
Abbreviation: HPF = high-power field

*Size represents the largest diameter.

 
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Last Updated: November 25, 2008