Part of Cancer staging guidance sheets
Small intestine (ICD10 C17)
Introduction
This is the data sheet for TNM 9th edition staging of the small intestine (ICD10 C17).
For more detailed information regarding TNM staging, please see pages 70-71 of the UICC TNM 9 book.
Stage groupings
|
Stage Group |
T stage |
N stage |
M stage |
|---|---|---|---|
|
Stage 0 |
Tis |
N0 |
M0 |
|
Stage I |
T1, T2 |
N0 |
M0 |
|
Stage IIA |
T3 |
N0 |
M0 |
|
Stage IIB |
T4 |
N0 |
M0 |
|
Stage IIIA |
Any T |
N1 |
M0 |
|
Stage IIIB |
Any T |
N2 |
M0 |
|
Stage IV |
Any T |
Any N |
M1 |
TNM clinical classification
T - primary tumour
|
T value |
Description |
|---|---|
|
cTX |
Primary tumour cannot be assessed |
|
cT0 |
No evidence of primary tumour |
|
cTis |
Carcinoma in situ |
|
cT1 |
Tumour invades lamina propria, muscularis mucosae or submucosa |
|
|
cT1a - Tumour invades lamina propria or muscularis mucosae |
|
|
cT1b - Tumour invades submucosa |
|
cT2 |
Tumour invades muscularis propria |
|
cT3 |
Tumour invades subserosa or non‐peritonealised perimuscular tissue (mesentery or retroperitoneum*) without perforation of the serosa |
|
cT4 |
Tumour perforates visceral peritoneum or directly invades other organs or structures (includes other loops of small intestine, mesentery, or retroperitoneum and abdominal wall by way of serosa; for duodenum only, invasion of pancreas) |
Note:
* The non‐peritonealised perimuscular tissue is, for jejunum and ileum, part of the mesentery and, for duodenum in areas where serosa is lacking, part of the retroperitoneum.
N - regional lymph nodes
|
N value |
Description |
|---|---|
|
cNX |
Regional lymph nodes cannot be assessed |
|
cN0 |
No regional lymph node metastasis |
|
cN1 |
Metastasis in 1 to 2 regional lymph nodes |
|
cN2 |
Metastasis in 3 or more regional lymph nodes |
M - distant metastasis
|
M value |
Description |
|---|---|
|
M0 |
No distant metastasis |
|
M1 |
Distant Metastasis |
TNM pathological classification
pT - primary tumour
The pT and pN categories correspond to the T and N categories as per above.
pN - regional lymph nodes
|
pN value |
Description |
|---|---|
|
pN0 |
Histological examination of a regional lymphadenectomy specimen should ordinarily include 6 or more lymph nodes. If the lymph nodes are negative, but the number ordinarily examined is not met, classify as pN0 |
Last edited: 16 January 2026 3:56 pm
