Staging-neuroendocrine tumors

Editorial Board Member: Diana Agostini-Vulaj, D.O.
Deputy Editor-in-Chief: Aaron R. Huber, D.O.
Raul S. Gonzalez, M.D.

Last author update: 17 May 2024
Last staff update: 17 May 2024

Copyright: 2003-2024,, Inc.

PubMed Search: Staging of gastric neuroendocrine tumors

Raul S. Gonzalez, M.D.
Page views in 2024 to date: 879
Cite this page: Gonzalez RS. Staging-neuroendocrine tumors. website. Accessed May 19th, 2024.
Definition / general
  • Well differentiated neuroendocrine tumors (NET) of the stomach are covered by this staging system
  • Not covered by this staging system are poorly differentiated neuroendocrine carcinomas of the stomach (use stomach carcinoma staging)
Essential features
  • AJCC 7th edition staging was sunset on December 31, 2017; as of January 1, 2018, use of the 8th edition is mandatory
  • AJCC 9th edition was released in 2023, with minimal changes from the 8th edition
ICD coding
  • ICD-10: C7A.092 - malignant carcinoid tumor of the stomach
Primary tumor (pT)
  • TX: primary tumor cannot be assessed
  • T0: no evidence of primary tumor
  • T1: tumor invades the mucosa or submucosa and is ≤ 1 cm in greatest dimension
  • T2: tumor invades the muscularis propria or is > 1 cm in greatest dimension
  • T3: tumor invades through the muscularis propria into subserosal tissue without penetration of overlying serosa
  • T4: tumor invades visceral peritoneum (serosa) or other organs or adjacent structures
Regional lymph nodes (pN)
  • NX: regional lymph nodes cannot be assessed
  • N0: no tumor involvement of regional lymph node(s)
  • N1: tumor involvement of regional lymph node(s)

  • 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)
  • cM0: no distant metastasis
  • cM1: distant metastasis
    • cM1a: metastasis confined to liver
    • cM1b: metastasis in at least 1 extrahepatic site (e.g., lung, ovary, nonregional lymph node, peritoneum, bone)
    • cM1c: both hepatic and extrahepatic metastasis
  • pM1: microscopic confirmation of distant metastasis
    • pM1a: microscopic confirmation of metastasis confined to liver
    • pM1b: microscopic confirmation of metastasis in at least 1 extrahepatic site (e.g., lung, ovary, nonregional lymph node, peritoneum, bone)
    • pM1c: microscopic confirmation of both hepatic and extrahepatic metastasis
  • c: clinical
  • p: pathological
  • yc: posttherapy clinical
  • yp: posttherapy pathological
Primary tumor suffix
  • (m): multiple synchronous primary tumors
Regional lymph nodes suffix
  • (f): fine needle aspiration (FNA) or core needle biopsy
AJCC prognostic stage groups
Stage I:  T1  N0, NX  M0
Stage II:  T2, T3  N0  M0
Stage III: T4  N0  M0
Stage III: any T   N1  M0
Stage IV:  any T  any N  M1
Prognostic tumor characteristics
  • Ki67 index
  • Mitotic count
  • Types of gastric NETs (type 1, 2, 3 or proton pump inhibitor [PPI] associated)
Registry data collection variables
  • Age
  • Procedure
  • Tumor site
  • Size of tumor (value or unknown)
  • Tumor focality
  • Depth of invasion
  • Lymphovascular invasion
  • Perineural invasion
  • Margin status
  • Nodal status (including number of lymph nodes assessed and number of positive nodes, if possible)
  • Sites of metastasis, if applicable
  • Ki67 index (value, unknown)
  • Mitotic count (value, unknown)
  • Grade (from Ki67 and mitotic count): G1, G2, G3, unknown
  • Preoperative gastrin level
  • Preoperative chromogranin A (CgA) level
  • Type of gastric NET (1, 2, PPI associated or 3)
Emerging factors for data collection
  • History of PPI use
Histologic grade (G)
  • G1: mitotic rate < 2 per 2 mm2 and Ki67 < 3%
  • G2: mitotic rate 2 - 20 per 2 mm2 or Ki67 3 - 20%
  • G3: mitotic rate > 20 per 2 mm2 or Ki67 > 20%
Histopathologic type
  • Neuroendocrine tumor, NOS
  • Neuroendocrine tumor, grade 1
  • Neuroendocrine tumor, grade 2
  • Neuroendocrine tumor, grade 3
  • Gastrin producing (G cell) neuroendocrine tumor
  • Serotonin producing enterochromaffin cell (EC cell) neuroendocrine tumor
  • Histamine producing enterochromaffin-like cell (ECL cell) neuroendocrine tumor
  • Somatostatinoma, NOS (D cell neuroendocrine tumor)
Residual tumor (operative factor)
  • R0: complete resection, margins histologically negative, no residual tumor left after resection
  • R1: incomplete resection, margins histologically involved, microscopic tumor remains after resection of gross disease (relevant to resection margins that are microscopically involved by tumor)
  • R2: incomplete resection, margins involved or gross disease remains
Board review style question #1
Based on AJCC 9th 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 style answer #1
C. pM1b. Metastasis to a nonhepatic distant site is categorized as pM1b; regional nodal metastases do not influence pM category staging. Answer A is incorrect because pM0 indicates there are no distant metastases. Answer B is incorrect because pM1a indicates only a hepatic distant metastasis. Answer D is incorrect because pM1c indicates both hepatic and extrahepatic distant metastases.

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Reference: Stomach - Staging-neuroendocrine tumors
Board review style question #2
Type of gastric neuroendocrine tumor (e.g., type 1 for atrophic gastritis associated NET) is used in which aspect of assessing and reporting these tumors?

  1. pN category staging
  2. pT category staging
  3. Registry data collection variables
  4. Tumor grading
Board review style answer #2
C. Registry data collection variables. Tumor type, among many other factors, is included in the AJCC list of registry data collection variables. Answers A and B are incorrect because tumor type does not affect staging of gastric neuroendocrine tumors. Answer D is incorrect because only Ki67 index and mitotic rate are used for grading of gastric neuroendocrine tumors.

Comment Here

Reference: Stomach - Staging-neuroendocrine tumors
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