Gastrointestinal Stromal Tumor Stages

After someone is diagnosed with cancer, doctors will try to figure out if it has spread, and if so, how far. This process is called staging. The stage of a cancer describes how much cancer is in the body. It helps determine how serious the cancer is and how best to treat it. Doctors also use a cancer's stage when talking about survival statistics.

The stages for gastrointestinal stromal tumors (GIST) range from stages I (1) through IV (4). As a rule, the lower the number, the less the cancer has spread. A higher number, such as stage IV, means cancer has spread more. And within a stage, an earlier letter means a lower stage. Although each person’s cancer experience is unique, cancers with similar stages tend to have a similar outlook and are often treated in much the same way.

How is the stage determined?

The staging system most often used for GIST tumors is the American Joint Committee on Cancer (AJCC) TNM system, which is based on 4 key pieces of information:

  • The extent of the tumor (T): How large is the cancer?
  • The spread to nearby lymph nodes (N): Has the cancer spread to nearby lymph nodes?
  • The spread (metastasis) to distant sites (M): Has the cancer spread to distant organs such as the liver?
  • 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 after T, N, and M provide more details about each of these factors. Higher numbers mean the cancer is more advanced. Once a person’s T, N, and M categories have been determined, this information is combined in a process called stage grouping to assign an overall stage. The stage grouping for GIST tumors depends on where the tumor starts:

  • The stomach or the omentum (The omentum is an apron-like layer of fatty tissue that hangs over the organs in the abdomen.) OR
  • 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 compared to GISTs that start in the stomach or omentum.)

For more information see Cancer Staging.

The staging system in the table below uses the pathologic stage (also called the surgical stage). It is determined by examining tissue removed during an operation. Sometimes, if surgery is not possible right away or at all, the cancer will be given a clinical stage instead. This is based on the results of a physical exam, biopsy, and imaging tests. The clinical stage will be used to help plan treatment. Sometimes, though, the cancer has spread further than the clinical stage estimates, and might not predict the patient’s outlook as accurately as a pathologic stage.

The system described below is the most recent AJCC system, effective January 2018. Cancer staging can be complex, so ask your doctor to explain it to you in a way you understand.

GIST that starts in the stomach or the omentum

 

AJCC stage

Stage grouping

Mitotic rate

Stage description*

IA

T1 or T2

N0

M0

Low

The cancer is:

  • 2 cm (4/5 of an inch) or less (T1) OR
  • Larger than 2 cm but not more than 5 cm (2 inches) (T2).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The mitotic rate is low.

IB

T3

N0

M0

Low

The cancer is larger than 5 cm (2 inches) but not more than 10 cm (T3).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The mitotic rate is low.

 

II

T1

N0

M0

High

The cancer is 2 cm or smaller (T1).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The mitotic rate is high.

OR

T2

N0

M0

High

The cancer is larger than 2 cm but not more than 5 cm (T2).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The mitotic rate is high.

OR

T4

N0

M0

Low

The cancer is larger than 10 cm (T4). It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The mitotic rate is low.

IIIA

 

T3

N0

M0

High

The cancer is larger than 5 cm (2 inches) but not more than 10 cm(T3).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The mitotic rate is high.

IIIB

T4

N0

M0

High

The cancer is larger than 10 cm (T4).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The mitotic rate is high.

IV

Any T

N1

M0

Any rate

The cancer is any size (Any T) AND it has spread to nearby lymph nodes (N1).

It has not spread to distant sites (M0). The cancer can have any mitotic rate.

OR

Any T

Any N

M1

Any rate

The cancer is any size (Any T) AND it might or might not have spread to nearby lymph nodes (Any N).

It has spread to distant sites such as the liver(M1). The cancer can have any mitotic rate.

*The following additional categories are not listed in the table above:

  • TX: Main tumor cannot be assessed due to lack of information.
  • T0: No evidence of a primary tumor.
  • NX: Regional lymph nodes cannot be assessed due to lack of information.

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

 

AJCC stage

Stage grouping

Mitotic rate

Stage description*

I

T1 or T2

N0

M0

Low

The cancer is:

  • 2 cm (4/5 of an inch) or less (T1) OR
  • Larger than 2 cm but not more than 5 cm (2 inches) (T2).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The mitotic rate is low.

 

II

T3

N0

M0

Low

The cancer is larger than 5 cm (2 inches) but not more than 10 cm(T3).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The mitotic rate is low.

IIIA

T1

N0

M0

High

The cancer is 2 cm or smaller (T1).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The mitotic rate is high.

OR

T4

N0

M0

Low

The cancer is larger than 10 cm (T4).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The mitotic rate is low.

IIIB

T2

N0

M0

High

The cancer is larger than 2 cm but not more than 5 cm (T2).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The mitotic rate is high.

OR

T3

N0

M0

High

The cancer is larger than 5 cm (2 inches) but not more than 10cm (T3).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The mitotic rate is high.

OR

T4

N0

M0

High

The cancer is larger than 10 cm (T4).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The mitotic rate is high.

IV

Any T

N1

M0

Any rate

The cancer is any size (Any T) AND it has spread to nearby lymph nodes (N1).

It has not spread to distant sites (M0). The cancer can have any mitotic rate.

OR

Any T

Any N

M1

Any rate

The cancer is any size (Any T) AND it might or might not have spread to nearby lymph nodes (Any N).

It has spread to distant sites such as the liver(M1). The cancer can have any mitotic rate.

*The following additional categories are not listed in the table above:

  • TX: Main tumor cannot be assessed due to lack of information.
  • T0: No evidence of a primary tumor.
  • NX: Regional lymph nodes cannot be assessed due to lack of information.

Resectable versus unresectable tumors

The AJCC staging system gives 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, if 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 Tumor. In: AJCC Cancer Staging Manual. 8th ed. New York, NY: Springer; 2017:523.

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: December 20, 2017 Last Revised: December 20, 2017

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