Gastrointestinal Stromal Tumor Stages

What is the stage of a cancer?

The stage of a cancer describes how far the cancer has spread. For many cancers, including gastrointestinal stromal tumors (GISTs), the stage is an important factor in selecting treatments and in predicting a person’s prognosis (outlook). To help stage the tumor, doctors use the results of physical exams and imaging, endoscopy, or other tests, such as those described in Tests for Gastrointestinal Stromal Tumors.

AJCC TNM staging system

Doctors use a staging system to describe the extent of spread of most types of cancer, including GISTs. The most common system used is the TNM system of the American Joint Committee on Cancer (AJCC). This system is based on 4 key pieces of information:

  • T describes the size of the primary tumor, measured in centimeters (cm).
  • N describes whether the cancer has spread to nearby (regional) lymph nodes (which is very rare for GISTs).
  • M indicates whether the cancer has metastasized (spread) to other organs of the body. If a GIST does spread, most often it is within the abdomen, such as to the liver. Less often, it may spread to the lungs and bones.
  • The mitotic rate is a lab test measurement of how fast the cancer cells are growing and dividing. It is described as either low or high. A low mitotic rate predicts a better outcome.

Numbers or letters appear after T, N, and M to provide more details about each of these factors.

T categories for GIST

TX: The primary (main) tumor cannot be assessed.

T0: No signs of a primary tumor.

T1: The tumor is 2 cm or less (about 4/5 of an inch) across.

T2: The tumor is larger than 2 cm across but not larger than 5 cm (about 2 inches).

T3: The tumor is larger than 5 cm across but not larger than 10 cm (about 4 inches).

T4: The tumor is larger than 10 cm across.

N categories for GIST

NX: Regional (nearby) lymph nodes cannot be assessed.

N0: The cancer has not spread to nearby lymph nodes.

N1: The cancer has spread to nearby lymph nodes.

M categories for GIST

M0: The cancer has not spread (metastasized) to distant organs or other parts of the body.

M1: The cancer has spread to distant organs (like the liver or the lungs) or other parts of the body.

Stages of GIST

Once the T, N, and M categories and the mitotic rate have been determined, this information is combined in a process called stage grouping. The overall stage is expressed in Roman numerals from I (the least advanced) to IV (the most advanced). The stage grouping depends on where the tumor starts.

GIST that starts in the stomach or the omentum*

*The omentum is an apron-like layer of fatty tissue that hangs over the organs in the abdomen.

Stage IA: T1 or T2, N0, M0, low mitotic rate: The tumor is no larger than 5 cm across (T1 or T2). The cancer has not spread to nearby lymph nodes (N0) or distant sites (M0). The mitotic rate is low.

Stage IB: T3, N0, M0, low mitotic rate: The tumor is larger than 5 cm but not larger than 10 cm across (T3). The cancer has not spread to nearby lymph nodes (N0) or distant sites (M0). The mitotic rate is low.

Stage II: One of the following applies:

  • T1 or T2, N0, M0, high mitotic rate: The tumor is no larger than 5 cm across (T1 or T2). The cancer has not spread to nearby lymph nodes (N0) or distant sites (M0). The mitotic rate is high.
  • T4, N0, M0, low mitotic rate: The tumor is larger than 10 cm across (T4). The cancer has not spread to nearby lymph nodes (N0) or distant sites (M0). The mitotic rate is low.

Stage IIIA: T3, N0, M0, high mitotic rate: The tumor is larger than 5 cm but not larger than 10 cm across (T3). The cancer has not spread to nearby lymph nodes (N0) or distant sites (M0). The mitotic rate is high.

Stage IIIB: T4, N0, M0, high mitotic rate: The tumor is larger than 10 cm across (T4). The cancer has not spread to nearby lymph nodes (N0) or distant sites (M0). The mitotic rate is high.

Stage IV: One of the following applies:

  • Any T, N1, M0, any mitotic rate: The tumor can be any size (any T). The cancer has spread to nearby lymph nodes (N1). It has not spread to distant sites (M0). The tumor can have any mitotic rate.
  • Any T, any N, M1, any mitotic rate: The tumor can be any size (any T) and it may or may not have spread to nearby lymph nodes (any N). The cancer has spread to distant sites, such as the liver or the lungs (M1). The tumor can have any mitotic rate.

GIST of the small intestine, esophagus, colon, rectum, or peritoneum**

**The peritoneum is a layer of tissue that lines the organs and walls of the abdomen.

Tumors in these locations are more likely to grow quickly than GISTs that start in the stomach or omentum.

Stage I: T1 or T2, N0, M0, low mitotic rate: The tumor is no larger than 5 cm across (T1 or T2). The cancer has not spread to nearby lymph nodes (N0) or distant sites (M0). The mitotic rate is low.

Stage II: T3, N0, M0, low mitotic rate: The tumor is larger than 5 cm but not larger than 10 cm across (T3). The cancer has not spread to nearby lymph nodes (N0) or distant sites (M0). The mitotic rate is low.

Stage IIIA: One of the following applies:

  • T1, N0, M0, high mitotic rate: The tumor is no larger than 2 cm across (T1). The cancer has not spread to nearby lymph nodes (N0) or distant sites (M0). The mitotic rate is high.
  • T4, N0, M0, low mitotic rate: The tumor is larger than 10 cm across (T4). The cancer has not spread to nearby lymph nodes (N0) or distant sites (M0). The mitotic rate is low.

Stage IIIB: T2 to T4, N0, M0, high mitotic rate: The tumor is larger than 2 cm across (T2 to T4). The cancer has not spread to nearby lymph nodes (N0) or distant sites (M0). The mitotic rate is high.

Stage IV: One of the following applies:

  • Any T, N1, M0, any mitotic rate: The tumor can be any size (any T). The cancer has spread to nearby lymph nodes (N1). It has not spread to distant sites (M0). The tumor can have any mitotic rate.
  • Any T, any N, M1, any mitotic rate: The tumor can be any size (any T) and it may or may not have spread to nearby lymph nodes (any N). The cancer has spread to distant sites, such as the liver or the lungs (M1). The tumor can have any mitotic rate.

Resectable versus unresectable tumors

The AJCC staging system provides a detailed summary of how far a GIST has spread. But for treatment purposes, doctors are often more concerned about whether the tumor can be removed (resected) completely with surgery.

Whether or not a tumor is resectable depends on its size and location, whether it has spread to other parts of the body, and if a person is healthy enough for surgery:

  • Tumors that can clearly be removed without causing major health problems are defined as resectable.
  • Tumors that can’t be removed completely (because they have spread or for other reasons) are described as unresectable.
  • In some cases, doctors may describe a tumor as marginally resectable or borderline resectable if it’s not clear if it can be removed completely.

If a tumor is considered unresectable or marginally resectable when it is first found, treatments such as targeted therapy may be used first to try to shrink the tumor enough to make it resectable.

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master’s-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

American Joint Committee on Cancer. Gastrointestinal stromal tumors. In: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer; 2010:175-180.

Casali PG, Dei Tos AP, Gronchi A. Chapter 55: Gastrointestinal Stromal Tumor. In: DeVita VT, Lawrence TS, Rosenberg SA, eds. DeVita, Hellman, and Rosenberg’s Cancer: Principles and Practice of Oncology. 10th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2015.

National Cancer Institute. Physician Data Query (PDQ). Gastrointestinal Stromal Tumors Treatment. 2017. Accessed at www.cancer.gov/types/soft-tissue-sarcoma/hp/gist-treatment-pdq on April 17, 2017.

National Comprehensive Cancer Network (NCCN). NCCN Clinical Practice Guidelines in Oncology: Soft Tissue Sarcoma. V.2.2017. Accessed at www.nccn.org/professionals/physician_gls/pdf/sarcoma.pdf on April 17, 2017.

Last Medical Review: May 17, 2017 Last Revised: May 17, 2017

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