Canadian Cancer Society logo

Small intestine
cancer

You are here: 

Neuroendocrine tumours of the small intestine

Neuroendocrine tumours (NETs) are cancers that develop in the diffuse neuroendocrine system. This system is made up of a network of specialized nerve-like cells that produce and release hormoneshormonesA substance that regulates specific body functions, such as metabolism, growth and reproduction. into the bloodstream. Neuroendocrine cells are scattered throughout the body, but are mainly found in the digestive system and respiratory system. The small intestine is one of the most common sites where gastrointestinal neuroendocrine cancers develop.

Neuroendocrine tumours account for 35% of all small intestine cancers. Their incidence is on the rise in Western countries.

Most neuroendocrine tumours of the small intestine occur in the ileum, the lower part of the small intestine. They are less common in the duodenum and jejunum.

Signs and symptoms

Neuroendocrine tumours are usually slow growing and can be present for many years. They usually start as small tumours about 1–5 cm (1/2 to 2 inches) in diameter. Because most NETs are small, they don’t usually cause symptoms. However, as the tumour grows, it can cause problems like blockage (obstruction), puncture (perforation) and bleeding.

About 10%–17% of people with small intestine neuroendocrine tumours present with carcinoid syndrome. Symptoms include skin flushing, diarrhea, sweating and abdominal cramping. These symptoms are caused by abnormal amounts of hormones in the bloodstream. There are usually multiple neuroendocrine tumours in the small intestine.

Back to top

Diagnosis

Doctors use blood work and imaging tests to diagnose NETs. They may also look for 5-hydroxyindoleacetic acid (5-HIAA), which is a tumour marker for some small intestine neuroendocrine tumours. 5-HIAA is a product of the breakdown of serotoninserotoninA type of neurotransmitter (a chemical that transmits signals or impulses from one neuron, or nerve cell, to another neuron cell or other specialized cells) that causes blood vessels to narrow and regulates the movement of the intestines.. Increased 5-HIAA levels are associated with neuroendocrine cancer. Doctors will check 5-HIAA levels in a 24-hour urine sample.

Chromogranin A (CgA) is another tumour marker that may be higher in people with gastrointestinal neuroendocrine tumours. Doctors will take a blood sample to measure CgA levels.

The majority of small intestine NETs are diagnosed when the disease has spread (metastasized) outside the small intestine to nearby structures or organs or to distant sites. The risk of cancer spreading is higher if the tumour is large and if it has grown through the wall of the small intestine.

Back to top

Staging

Staging is a way of describing or classifying a cancer based on the extent of cancer in the body.Well-differentiated neuroendocrine cancers of the small intestine are staged slightly differently than other carcinomas of the small intestine. The most common staging system for neuroendocrine tumours of the small intestine is the TNM system.

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

T1

Tumour invades the lamina propria or submucosa and is no more than 1 cm (0.4 inch) in size.

T2

Tumour invades the muscularis propria or is greater than 1 cm in size.

T3

Tumour in the jejunum or ileum invades the subserosa.

Tumour in the duodenum invades the pancreas or retroperitoneum (back of the abdominal cavity).

T4

Tumour perforates the visceral peritoneum (serosa) or invades other organs or nearby (adjacent) tissues.

Regional lymph nodes (N)

NX

Regional lymph nodes cannot be assessed

N0

No regional lymph node metastasis

N1

Regional lymph node metastasis

Distant metastasis (M)

M0

No distant metastasis

M1

Distant metastasis

Stage grouping for neuroendocrine tumours of the small intestine

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

UICC staging – small intestine neuroendocrine cancer

UICC stage

TNM

Explanation

stage I

T1

N0

M0

The tumour has grown into the lamina propria or the submucosa and is 1 cm or less in size.

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

stage IIA

T2

N0

M0

The tumour has grown into the muscularis propria or is greater than 1 cm in size.

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

stage IIB

T3

N0

M0

Tumours in the jejunum or ileum have grown into the subserosa. Tumours in the duodenum have grown into the pancreas or retroperitoneum (back of the abdominal cavity).

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

stage IIIA

T4

N0

M0

The tumour has perforated the serosa of the small intestine or has spread to nearby organs or structures.

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

stage IIIB

any T

N1

M0

The tumour is any size and has spread to 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 intestinal neuroendocrine cancer

Recurrent small intestinal neuroendocrine 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 neuroendocrine cancer).

Back to top

Stories

Researcher Dr John Bell Fighting cancer with designer viruses

Read more

Volunteers provide comfort and kindness

Illustration of volunteers

Thousands of Canadian Cancer Society volunteers work in regional cancer centres, lodges and community hospitals to support people receiving treatment.

Learn more