Radiation Oncology/Stomach/Staging

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* (see note below)

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)