Small bowel (small intestine)
Staging - GIST

Author: Hanni Gulwani, M.D. (see Authors page)

Revised: 27 February 2018, last major update August 2012

Copyright: (c) 2003-2018,, Inc.

PubMed Search: Staging GIST small bowel

Cite this page: Gulwani, H. Staging - GIST. website. Accessed July 15th, 2018.
Definition / general
  • Staging system also used for GIST of esophagus, colorectum, mesentery and peritoneum
Primary tumor (T)
  • TX: Primary tumor cannot be assessed
  • T0: No evidence for primary tumor
  • T1: Tumor 2 cm or less
  • T2: Tumor more than 2 cm but not more than 5 cm
  • T3: Tumor more than 5 cm but not more than 10 cm
  • T4: Tumor more than 10 cm in greatest dimension

  • For ruptured tumors, use radiologic data to estimate tumor size
Regional lymph nodes (N)
  • N0: No regional lymph node metastasis
  • N1: Regional lymph node metastasis

  • Nodal metastases are extremely rare in GIST so there is no routine indication for lymph node biopsy or lymph node dissection
  • Use N0 / pN0 if no information on nodal status; do not use NX
Distant metastasis (M)
  • M0: No distant metastasis
  • M1: Distant metastasis (specify site, if known)

  • Most GISTs metastasize to intra-abdominal soft tissue or liver
  • Intra-abdominal metastasis refers to tumor involvement in abdominal cavity away from the primary mass, usually to serosal surfaces of abdomen, pelvis, retroperitoneum
  • Multiple primary tumors are associated with neurofibromatosis type 1 or familial GIST syndrome and should not be considered intra-abdominal metastasis, although rare cases of multiple independent GISTs at different GI locations have been reported
  • If no primary GI GIST is identified, solitary omental, mesenteric, pelvic or retroperitoneal GISTs should be considered primary tumors
  • Liver metastasis implies metastatic tumor inside the liver parenchyma as 1 or more nodules but adherence to liver capsule, even if extensive, should not be considered liver metastasis
Anatomic stage / prognostic groups
  • Stage IA: T1 - 2 N0 M0 and low mitotic rate
  • Stage IB: T3 N0 M0 and low mitotic rate
  • Stage II: T1 - 2 N0 M0 and high mitotic rate or T4 N0 M0 and low mitotic rate
  • Stage IIIA: T1 N0 M0 and high mitotic rate or T4 N0 M0 and low mitotic rate
  • Stage IIIB: T2 - 4 N0 M0 and high mitotic rate
  • Stage IV: N1 or M1

  • Low mitotic rate: 5 or fewer per 50 HPF
  • High mitotic rate: over 5 per 50 HPF
  • Required total count of mitoses is per 5 mm2 on the glass slide (50 HPF for older microscopes, 20 HPF for newer microscopes)
Diagrams / tables

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Guidelines for risk assessment of primary GIST