Small intestine

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Cancerous tumours of the small intestine

A cancerous tumour of the small intestine can invade, or grow into, and destroy nearby tissue. It can also spread, or metastasize, to other parts of the body. Cancerous tumours are also called malignant tumours.


Adenocarcinoma starts in the gland cells in the inner lining (called the mucosa) of the wall of the small intestine. Most small intestine adenocarcinomas develop in the duodenum (the first part of the small intestine, which is connected to the stomach).

These tumours often block the small intestine as they grow. In most cases, small intestine adenocarcinoma has already spread, or metastasized, to other parts of the body when it is diagnosed.

Adenocarcinoma is the second most common type of tumour found in the small intestine. The information about small intestine cancer focuses on adenocarcinoma of the small intestine.

Other cancerous tumours

The following are other types of cancerous tumours that develop in the small intestine. They are treated differently than small intestine adenocarcinoma.

Neuroendocrine tumours

Neuroendocrine tumours (NETs) develop in neuroendocrine cells. These cells have a structure similar to nerve cells, or neurons. They also make hormones like endocrine cells.

Most small intestine NETs are found in the ileum (the last part of the small intestine, which connects to the large intestine).

NETs have become the most common type of tumour diagnosed in the small intestine. Experts don’t know why people in Western countries are developing these tumours more often than in the past.

Find out more about neuroendocrine cancer, including treatment options.


Lymphoma is a type of cancer that develops in the lymphocytes. Lymphocytes are white blood cells that circulate in the lymph fluid, mainly through the lymphatic system. It is the third most common type of cancer of the small intestine. Most lymphomas are found in the ileum.

The 2 main types of lymphoma are Hodgkin lymphoma and non-Hodgkin lymphoma. Hodgkin lymphoma of the small intestine is very rare. Almost all small intestine lymphomas are non-Hodgkin lymphomas (NHL). The types of NHL that can develop in the small intestine are:

  • diffuse large B-cell lymphoma (DLBCL)
  • mantle cell lymphoma
  • Burkitt and Burkitt-like lymphoma
  • extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma)
  • follicular lymphoma
  • enteropathy-associated T-cell lymphoma

Find out more about the different types of non-Hodgkin lymphoma and how they are treated

Soft tissue sarcoma

Sarcoma is a type of cancer that can develop in any soft tissue in the body, including the small intestine.

Most sarcomas found in the small intestine are gastrointestinal stromal tumours (GISTs). The following types of soft tissue sarcoma can also develop in the small intestine, but they are rare:

  • leiomyosarcoma (a type of cancer that develops in smooth muscle)
  • Kaposi sarcoma (a type of cancer that starts in cells that line the lymph or blood vessels)
  • malignant fibrous histiocytoma (a type of cancer that develops in fibrous tissues)

Find out more about soft tissue sarcoma, including treatment options.


Melanoma is a cancerous tumour that starts in melanocytes. Melanocytes are a type of cell that makes melanin, which is the pigment that gives your skin and eyes their colour.

Melanoma that starts in the small intestine is very rare. Experts think that most melanomas found in the small intestine may have started in the skin, but the original tumour can’t be found.

Melanoma in the small intestine is treated with surgery. Doctors remove the part of small intestine where the tumour is found, along with the lymph nodes in the area. There is no standard chemotherapy plan for small intestine melanoma, but doctors may offer the same targeted therapy or chemotherapy drugs used for melanoma of the skin. Find out more about treatments for melanoma.

lymphatic system

The group of tissues and organs that produce and store cells that fight infection and diseases.

The lymphatic system includes the adenoids, tonsils, spleen, thymus, lymph nodes, lymph vessels and bone marrow.

Also called the lymph system.

soft tissue

The soft tissues in the body (distinct from bone and cartilage).

Soft tissue includes muscle, fat, fibrous tissue, blood vessels and other tissues that support structures and organs in the body.