STOMACH (ICD‐O‐3 C16)
Rules for Classification
The classification applies only to carcinomas. There should be histological confirmation of the disease. Cancers involving the oesophagogastric junction whose epicentre is within the proximal 2 cm of the cardia (Siewert types I/II) are to be staged as oesophageal cancers. Cancers whose epicentre is more than 2 cm distal from the oesophagogastric junction will be staged using the Stomach Cancer TNM and Stage even if the oesophagogastric junction is involved.
Anatomical Subsites (Fig. 142)
- Fundus (C16.1)
- Corpus (C16.2)
- Antrum (C16.3) and pylorus (C16.4)
Regional Lymph Nodes (Figs. 143, 144)
The regional lymph nodes of the stomach are the perigastric nodes along the lesser (1, 3, 5) and greater (2, 4a, 4b, 6) curvatures, the nodes along the left gastric (7), common hepatic (8), splenic (11) and coeliac arteries (9), and the hepatoduodenal nodes (12).
Involvement of other intra‐abdominal lymph nodes such as retropancreatic, mesenteric and para‐aortic is classified as distant metastasis.
TNM Clinical Classification
T – Primary Tumour
TX | Primary tumour cannot be assessed | ||
T0 | No evidence of primary tumour | ||
Tis | Carcinoma in situ: intraepithelial tumour without invasion of the lamina propria, high‐grade dysplasia | ||
T1 | Tumour invades lamina propria, muscularis mucosae or submucosa (Fig. 145) | ||
T1a | Tumour invades lamina propria or muscularis mucosae | ||
T1b | Tumour invades submucosa | ||
T2 | Tumour invades muscularis propria (Fig. 145) | ||
T3 | Tumour invades subserosa (Figs. 145, 146, 147) | ||
T4 | Tumour perforates serosa (visceral peritoneum) or invades adjacent structures1,2,3 | ||
T4a | Tumour perforates serosa | ||
T4b | Tumour invades adjacent structures2, 3 (Fig. 148) |






Notes
The adjacent structures of the stomach are the spleen, transverse colon, liver, diaphragm, pancreas, abdominal wall, adrenal gland, kidney, small intestine and retroperitoneum.
Intramural extension to the duodenum or oesophagus is classified by the depth of greatest invasion in any of these sites including the stomach (Figs. 147, 149).
Tumour that extends into gastrocolic or gastrohepatic ligaments or into greater or lesser omentum, without perforation of visceral peritoneum, is T3 (Fig. 150).



N – Regional Lymph Nodes
NX | Regional lymph nodes cannot be assessed | ||
N0 | No regional lymph node metastasis | ||
N1 | Metastasis in 1 to 2 regional lymph nodes (Fig. 151) | ||
N2 | Metastasis in 3 to 6 regional lymph nodes (Fig. 152) | ||
N3 | Metastasis in 7 or more regional lymph nodes | ||
N3a | Metastasis in 7 to 15 regional lymph nodes (Fig. 153) | ||
N3b | Metastasis in 16 or more regional lymph nodes (Fig. 154) |
M – Distant Metastasis
M0 | No distant metastasis |
M1 | Distant metastasis (Fig. 154) |
Note
Distant metastasis includes peritoneal seeding, positive peritoneal cytology, and omental tumour not part of continuous extension.
pTNM Pathological Classification
The pT and pN categories correspond to the T and N categories.
pM1 | Distant metastasis microscopically confirmed |
pN0 | Histological examination of a regional lymphadenectomy specimen will ordinarily include 16 or more lymph nodes. If the lymph nodes are negative, but the number ordinarily examined is not met, classify as pN0 |
Note
pM0 and pMX are not valid categories.




Summary

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