Canadian Cancer Society logo

Small intestine

You are here: 

What is small intestine cancer?

Small intestine cancer is a malignant tumour that starts in cells of the small intestine. Malignant means that it can spread, or metastasize, to other parts of the body.

The small intestine, or small bowel, is part of the digestive system. It is a hollow, tube-like organ in the abdomen. The small intestine is made up of the duodenum, jejunum and ileum. The duodenum receives partially digested food from the stomach. Digestive juices and bile are added to the food in the duodenum, and then the food is passed to the jejunum. The jejunum breaks the food down more, absorbs nutrients and passes digested food to the ileum. The ileum absorbs nutrients and passes what is left to the large intestine.

Cells in the small intestine sometimes change and no longer grow or behave normally. These changes can cause precancerous conditions. This means that the cells are not yet cancer but there is a higher chance these abnormal changes will become cancer. The most common precancerous condition of the small intestine is an adenomatous polyp, or adenoma.

In some cases, changes to cells in the small intestine can cause cancer. Cancer that starts in the gland cells in the lining of the small intestine is called an adenocarcinoma of the small intestine.

Other types of cancer can also start in the small intestine. Neuroendocrine tumours start in the neuroendocrine cells of the small intestine. Lymphoma is a type of cancer that starts in lymph tissue of the small intestine. Sarcoma is a type of cancer that can start in the wall of the small intestine.

Diagram of the digestive system


Dr John Dick Solving the mysteries of cancer stem cells

Read more

Advocating for cancer patients

Illustration of a bullhorn

Our staff and volunteers meet with elected officials from local, provincial and national governments to persuade them to make the fight against cancer one of their top priorities.

Learn more