Soft tissue
Staging
Gastrointestinal stromal tumor

Author: Faizan Malik, M.B.B.S. (see Authors page)
Senior Author: Michael R. Clay, M.D.
Editor-in-Chief Review: Debra Zynger, M.D.

Revised: 5 December 2018, last major update November 2018

Copyright: (c) 2018, PathologyOutlines.com, Inc.

PubMed Search: Staging soft tissue gastrointestinal stromal tumor

Cite this page: Malik F, Clay MR. Staging - gastrointestinal stromal tumor. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/softtissuestaginggist.html. Accessed December 16th, 2018.

Pathologic TNM staging of gastrointestinal stromal tumor, AJCC 8th edition
Introduction
  • Histologic grading for gastrointestinal stromal tumor (GIST) is different from other sarcomas and depends on the mitotic rate per 5 mm2, which roughly corresponds to 50 high power fields (HPF) in older microscopes and 20 - 25 HPF in newer microscopes
    • Number of fields necessary should be determined for individual microscopes
  • AJCC prognostic stage grouping for gastric and omental GISTs is different from GISTs of small intestine, esophagus, colon / rectum, mesentery and peritoneum; therefore, the appropriate table / section should be consulted
  • Pediatric GIST, familial GIST (germline mutant KIT or PDGFRA) or syndromic GIST are not staged according to the AJCC system
Primary tumor (pT)
  • pTX: Primary tumor cannot be assessed
  • pT0: No evidence of primary tumor
  • pT1: Tumor ≤ 2 cm in greatest dimension
  • pT2: Tumor > 2 cm and ≤ 5 cm
  • pT3: Tumor > 5 cm and ≤ 10 cm
  • pT4: Tumor > 10 cm in greatest dimension

Notes:
  • In cases in which a tumor is received ruptured, the largest diameter may need to be estimated from imaging studies
  • Although tumor rupture into the peritoneal cavity significantly increases the risk of peritoneal recurrence and should be recorded, it is not yet included in the staging system due to inadequate data
Regional lymph nodes (pN)
  • pN0: No regional lymph node metastasis
  • pN1: Regional lymph node metastasis

Notes:
  • pNX is not used for soft tissue tumors and no pN should be reported if no lymph nodes are present
Distant metastasis (pM)
  • pM1: Distant metastasis
Histologic grade (G)
  • Low mitotic rate: ≤ 5 mitoses per 5 mm2
  • High mitotic rate: > 5 mitoses per 5 mm2
AJCC prognostic stage groups

  AJCC stage     Stage grouping   Gastric and omental GIST stage
IA T1 or T2 Tumor is ≤ 2 cm in greatest dimension (T1) OR tumor is > 2 cm and ≤ 5 cm (T2)
N0 It has not spread to regional lymph nodes (N0)
M0 It has not spread to distant sites (M0)
Low mitotic rate There are ≤ 5 mitoses per 5 mm2
IB T3 Tumor is > 5 cm and ≤ 10 cm (T3)
N0 It has not spread to regional lymph nodes (N0)
M0 It has not spread to distant sites (M0)
Low mitotic rate There are ≤ 5 mitoses per 5 mm2
II T1 or T2 Tumor is ≤ 2 cm in greatest dimension (T1) OR tumor is > 2 cm and ≤ 5 cm (T2)
N0 It has not spread to regional lymph nodes (N0)
M0 It has not spread to distant sites (M0)
High mitotic rate There are > 5 mitoses per 5 mm2
OR
T4 Tumor is > 10 cm in greatest dimension (T4)
N0 It has not spread to regional lymph nodes (N0)
M0 It has not spread to distant sites (M0)
Low mitotic rate There are ≤ 5 mitoses per 5 mm2
IIIA T3 Tumor is > 5 cm but ≤ 10 cm (T3)
N0 It has not spread to nearby lymph nodes (N0)
M0 It has not spread to distant sites (M0)
High mitotic rate There are > 5 mitoses per 5 mm2
IIIB T4 Tumor is > 10 cm (T4)
N0 It has not spread to nearby lymph nodes (N0)
M0 It has not spread to distant sites (M0)
High mitotic rate There are > 5 mitoses per 5 mm2
IV Any T Cancer is any size (any T) AND
N1 It has spread to nearby lymph nodes (N1)
M0 It has not spread to distant sites (M0)
Any mitotic rate It can have any number of mitoses
OR
Any T Cancer is any size (any T) AND
Any N It has or has not spread to nearby lymph nodes (any N)
M1 It has spread to distant sites such as the lungs (M1)
Any mitotic rate It can have any number of mitoses


  AJCC stage     Stage grouping     Small intestinal, esophageal, colorectal, mesenteric and peritoneal GIST stage  
I T1 or T2 Tumor is ≤ 2 cm in greatest dimension (T1) OR tumor is > 2 cm and ≤ 5 cm (T2)
N0 It has not spread to regional lymph nodes (N0)
M0 It has not spread to distant sites (M0)
Low mitotic rate There are ≤ 5 mitoses per 5 mm2
II T3 Tumor is > 5 cm and ≤ 10 cm (T3)
N0 It has not spread to regional lymph nodes (N0)
M0 It has not spread to distant sites (M0)
Low mitotic rate There are ≤ 5 mitoses per 5 mm2
IIIA T1 Tumor is ≤ 2 cm in greatest dimension (T1)
N0 It has not spread to regional lymph nodes (N0)
M0 It has not spread to distant sites (M0)
High mitotic rate There are > 5 mitoses per 5 mm2
OR
T4 Tumor is > 10 cm in greatest dimension (T4)
N0 It has not spread to regional lymph nodes (N0)
M0 It has not spread to distant sites (M0)
Low mitotic rate There are ≤ 5 mitoses per 5 mm2
IIIB T2, T3 or T4 Tumor is > 5 cm in greatest dimension (T2, T3 or T4)
N0 It has not spread to nearby lymph nodes (N0)
M0 It has not spread to distant sites (M0)
High mitotic rate There are > 5 mitoses per 5 mm2
IV Any T Cancer is any size (any T) AND
N1 It has spread to nearby lymph nodes (N1)
M0 It has not spread to distant sites (M0)
Any mitotic rate It can have any number of mitoses
OR
Any T Cancer is any size (any T) AND
Any N It has or has not spread to nearby lymph nodes (any N)
M1 It has spread to distant sites such as the lungs (M1)
Any mitotic rate It can have any number of mitoses

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