# Radiation Oncology/Stomach/Staging

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## Current Staging

AJCC 7th Edition (2009) Staging applies only to carcinomas. Lymphomas, sarcomas, and carcinoids not included. Note: tumors of the esophagogastric junction or arising in the stomach <= 5 cm from the EGJ and crossing the EGJ are staged as Esophageal cancers
T-stage:
* Tis - in situ; no invasion of lamina propria
* T1 - (mucosal invasion) invades lamina propria, muscularis mucosae, or submucosa
** T1a - invades lamina propria or muscular mucosae
** T1b - invades submucosa
* T2 - (wall invasion) invades muscularis propria
* T3 - penetrates subserosal connective tissue without invasion of visceral peritoneum or adjacent structures
* T4 - invades serosa (visceral peritoneum) or adjacent structures
** T4a - invades serosa (visceral peritoneum)
** T4b - invades adjacent structures
*** adjacent structures include: spleen, transverse colon, liver, diaphragm, pancreas, abdominal wall, adrenal gland, kidney, small intestine, and retroperitoneum
note: intramural extension to the duodenum or esophagus is classified by the depth of greatest invasion
N-stage: (should include 10-15 nodes for analysis)
* N0 - no nodes
* N1 - 1-2 nodes
* N2 - 3-6 nodes
* N3 - 7 or more nodes
** N3a - 7-15 nodes
** N3b - 16 or more nodes
Regional nodes include:
* Greater curvature: greater curvature, greater omental, gastroduodenal, gastroepiploic, pyloric, pancreaticoduodenal
* Pancreatic and splenic area: pancreaticolienal, peripancreatic, splenic
* Lesser curvature: lesser curvature, lesser omental, left gastric, cardioesophageal, common hepatic, celiac, hepatoduodenal$^*$ $^{(seenotebelow)}$
Involvement of other nodal groups (retropancreatic, para-aortic, portal, retroperitoneal, and mesenteric) are considered distant metastases. Positive peritoneal cytology is classified as metastatic disease. $^{*(note)}$The manual states "Involvement of other intra-abdominal lymph nodes, such as the hepatoduodenal ... is classified as distant metastasis." (Confusing. It lists hepatoduodenal nodes are both metastatic and regional)
M-stage:
* M0 - no
* M1 - yes
Stage grouping:
* IA - (add to 1) T1N0
* IB - (add to 2) T1N1 or T2N0
* IIA - (add to 3) T1N2, T2N1, T3N0
* IIB - (add to 4) T1N3, T2N2, T3N1, T4aN0
* IIIA - (add to 5) T2N3, T3N2, T4aN1
* IIIB - (add to 6 or T4b) T3N3, T4a N2, T4b N1, T4b N0
* IIIC - T4aN3, T4b N2-3
* IV - Any M1
Changes from 6th edition:
* Cancers of the GE junction and proximal 5 cm of stomach are classified as esophageal cancers
* Subdivision of T1 into T1a/b
* Redefined T2 (same as old T2a). Also, T2 is no longer subdivided.
* Redefined T3 (same as old T2b).
* Redefined and subdivided T4. T4a is same as old T3. T4b is same as old T4.
* Changed # lymph nodes involved to define N1/2/3
* Redefined stage groupings

## Older staging editions

AJCC 6th Edition (2002) T-stage:
* Tis - in situ; no invasion of lamina propria
* T1 - (mucosal invasion) invades lamina propria or submucosa
* T2 - (wall invasion) invades muscularis propria or subserosa
** T2a - muscularis propria
** T2b - subserosa
* T3 - penetrates serosa (visceral peritoneum) without invasion of adjacent structures
* T4 - invades adjacent structures
N-stage: (should include 10-15 nodes for analysis)
* N0 - no nodes
* N1 - 1-6 nodes
* N2 - 7-15 nodes
* N3 - more than 15 nodes
Stage grouping:
* IA - (add to 1) T1N0
* IB - (add to 2) T1N1 or T2N0
* II - (add to 3) T1N2, T2N1, T3N0
* IIIA - (add to 4) T2N2, T3N1, T4N0
* IIIB - (add to 5) T3N2
* IV - Any T4N+, Any N3, or M1
Changes in 6th edition: divided T2 into T2a and T2b
AJCC 5th Edition (1997)
* No subdivision of T2 into T2a and T2b.
* Changed N-staging
AJCC 4th edition (1992)
* N1: positive node located with 3cm of primary. N2: located more than 3 cm of primary.

## Japanese Staging

* Japanese Classification, 3rd English Edition (2011)