© 2005-2012 American Society of Clinical Oncology (ASCO). All rights reserved worldwide.
Staging is a way of describing where a tumor is located, if or where it has spread, and whether it is affecting the functions of other organs in the body. Doctors use diagnostic tests to determine 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 (chance of recovery). There are different stage descriptions for different types of tumors.
There is no standard staging system for DIG; however, it is classified by the World Health Organization (WHO) as a grade I nervous system tumor. The four-stage (I to IV) WHO system is described below:
WHO grade I: Includes distinct, unconnected tumors that are less likely to spread and can often be successfully treated with only the surgical removal of the tumor. (This is the grade given to DIG by the WHO.)
WHO grade II: Includes tumors that are likely to spread and have low numbers of dividing tumor cells that may come back after treatment. Some tumor types tend to progress to a higher grade (become more aggressive).
WHO grade III: Includes tumors that have cancerous characteristics, such as dividing tumor cells, evidence of spreading, and undifferentiated cells (cells that look less like normal cells when viewed under a microscope).
WHO grade IV: Includes tumors that have actively dividing tumor cells, areas of tumor cell death, and generally grow rapidly both before and after surgery.
Recurrent: A recurrent tumor is a tumor that comes back after treatment. If there is a recurrence, the tumor may need to be graded again using the system above.