Stomach
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TNM staging of neuroendocrine tumors of the stomach (AJCC 8th edition)

Author: Raul S. Gonzalez, M.D.
Editor-in-Chief Review: Debra Zynger, M.D.

Revised: 13 August 2018, last major update August 2018

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

PubMed Search: TNM staging stomach neuroendocrine tumor
Cite this page: Gonzalez, R.S. TNM staging of neuroendocrine tumors of the stomach (AJCC 8th edition). PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/stomachstagingneuroendocrine.html. Accessed October 18th, 2018.

Pathologic TNM staging of neuroendocrine tumors of the stomach, AJCC 8th edition
Definition / general
  • Well differentiated neuroendocrine tumors of the stomach are covered by this staging system
  • Not covered by this staging system are poorly differentiated neuroendocrine carcinomas of the stomach (click here)
ICD-10 coding
  • C7A.092: Malignant carcinoid tumor of the stomach
Primary tumor (pT)
  • TX: Primary tumor cannot be assessed
  • T0: No evidence of primary tumor
  • T1: Invades the lamina propria or submucosa and is ≤ 1 cm in size
  • T2: Invades the muscularis propria or is > 1 cm in size
  • T3: Invades through the muscularis propria into subserosal tissue without penetration of overlying serosa
  • T4: Invades visceral peritoneum (serosa) or other organs or adjacent structures
Regional lymph nodes (pN)
  • NX: Regional lymph nodes cannot be assessed
  • N0: No regional lymph node metastasis has occurred
  • N1: Regional lymph node metastasis

Notes:
  • Regional lymph nodes depend on the tumor site within the stomach:
    • Greater curvature: greater curvature, greater omental, gastroduodenal, gastroepiploic, pyloric, and pancreaticoduodenal nodes
    • Pancreatic and splenic areas: pancreaticolienal, peripancreatic, and splenic nodes
    • Lesser curvature: lesser curvature, lesser omental, left gastric, cardioesophageal, common hepatic, celiac, and hepatoduodenal nodes
Distant metastasis (pM)
  • M0: No distant metastasis
  • M1: Distant metastasis
    • M1a: Metastasis confined to liver
    • M1b: Metastasis in at least one extrahepatic site (e.g., lung, ovary, nonregional lymph node, peritoneum, bone)
    • M1c: Both hepatic and extrahepatic metastasis
Prefixes
  • (m): multiple primary lesions (provide stage for the most advanced lesion)
  • r: recurrent tumor stage
Stage grouping
Stage I: T1 N0 M0
Stage II: T2 - 3  N0 M0
Stage III: T4 N0 M0
any T N1 M0
Stage IV:any T any N  M1
Registry data collection variables
  • Size of tumor (value or unknown)
  • Depth of invasion
  • Nodal status and number of nodes involved, if applicable
  • Sites of metastasis, if applicable
  • Ki67 index
  • Mitotic count
  • Histologic grading (from Ki67 and mitotic count): G1, G2, G3
  • Preoperative pancreastatin level
  • Preoperative gastrin level
  • Preoperative CgA level
  • Type of gastric neuroendocrine tumor (NET) (I, II, or III)
Histologic grade
  • Grading is not formally part of the staging system
  • Most pathologists use the European Neuroendocrine Tumor Society (ENETS) /WHO grading criteria:
    • Grade 1: Mitotic rate < 2 per 10 high power fields and Ki67 rate < 3%
    • Grade 2: Mitotic rate 2 - 20 per 10 high power fields or Ki67 rate 3 - 20%
    • Grade 3: Mitotic rate > 20 per 10 high power fields or Ki67 rate > 20%
Histopathologic type
  • Neuroendocrine tumor (NET) G1 (carcinoid)
  • Neuroendocrine tumor (NET) G2
Board review question #1
    Based on AJCC 8th edition criteria, a well differentiated neuroendocrine tumor of the stomach that metastasized to regional lymph nodes and also to the lung would be staged as which of the following?

  1. pM0
  2. pM1a
  3. pM1b
  4. pM1c
Board review answer #1
C. pM1b

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