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Stages of small intestine cancer

Staging is a way of describing or classifying a cancer based on the extent of cancer in the body. The most common staging system for small intestine cancer is the TNM system. The International Union Against Cancer (UICC) uses the TNM system to describe the extent of many solid tumour cancers.

The TNM staging below is used only for carcinomas of the small intestine. Neuroendocrine tumours, lymphomas and sarcomas of the small intestine are staged differently.

TNM

TNM stands for tumour, nodes, metastasis. TNM staging describes:

  • the size of the primary tumour
  • the number and location of any regional lymph nodes that have cancer cells in them
  • whether the cancer has spread or metastasized to another part of the body

Primary tumour (T)

TX

Primary tumour cannot be assessed

T0

No evidence of primary tumour

Tis

Carcinoma in situ

T1

Tumour invades the lamina propria, muscularis mucosa or submucosa.

T1a – Tumour invades the lamina propria or muscularis mucosa.

T1b – Tumour invades the submucosa.

T2

Tumour invades the muscularis propria.

T3

Tumour invades 2 cm (0.8 inch) or less into the subserosa or into the non-peritonealized perimuscular tissue (mesentery or retroperitoneum*).

T4

Tumour perforates the visceral peritoneum or directly invades other organs or structures, including:

  • other loops of the small intestine, mesentery or retroperitoneum by more than 2 cm
  • through the serosa into the abdominal wall
  • the pancreas (only for tumours in the duodenum)

*Note: The non-peritonealized perimuscular tissue for the jejunum and ileum is part of the mesentery. For the duodenum, it is part of the retroperitoneum in areas where there is no serosa.

Regional lymph nodes (N)

NX

Regional lymph nodes cannot be assessed

N0

No regional lymph node metastasis

N1

Metastasis in 1–3 regional lymph nodes

N2

Metastasis in 4 or more regional lymph nodes

Distant metastasis (M)

M0

No distant metastasis

M1

Distant metastasis

Stage grouping for small intestine cancer

The UICC further groups the TNM data into the stages listed in the table below.

UICC staging – small intestine cancer
UICC stageTNMExplanation

stage 0

Tis

N0

M0

Carcinoma in situ. Cancer cells are only in the epithelium of the mucosa (the innermost layer of tissue in the small intestine).

stage I

T1, T2

N0

M0

Cancer has grown through the inner layers of the small intestine into either:

  • lamina propria or muscularis mucosa
  • muscularis propria

It has not spread to nearby lymph nodes or distant parts of the body.

stage IIA

T3

N0

M0

Cancer has grown through the wall of the small intestine and extends into one of the following by 2 cm or less:

  • subserosa
  • mesentery (the membrane that attaches the small intestine to the back of the abdominal wall)
  • retroperitoneum (back of the abdominal cavity)

It has not spread to nearby lymph nodes or distant parts of the body.

stage IIB

T4

N0

M0

Cancer has grown through the wall of the small intestine, into the serosa and either perforates the visceral peritoneum (the membrane that covers organs inside the abdomen) or has spread to nearby organs or structures including:

  • other loops of the small intestine, mesentery or retroperitoneum by more than 2 cm
  • through the serosa into the abdominal wall
  • the pancreas (only for tumours in the duodenum)

It has not spread to nearby lymph nodes or distant parts of the body.

stage IIIA

any T

N1

M0

The tumour is any size and has spread to 1–3 nearby lymph nodes.

It has not spread to distant parts of the body.

stage IIIB

any T

N2

M0

The tumour is any size and has spread to 4 or more nearby lymph nodes.

It has not spread to distant parts of the body.

stage IV

any T

any N

M1

The tumour is any size and may or may not have spread to nearby lymph nodes.

It has spread to distant parts of the body.

Recurrent small intestine cancer

Recurrent small intestine cancer means that the cancer has come back after it has been treated. It may recur in the same location as the original cancer or it may recur in another part of the body (metastatic small intestine cancer).

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