Overview

A gastrointestinal stromal tumor, also called a GIST, is a type of cancer that begins in the digestive system. GISTs happen most often in the stomach and small intestine.

A GIST is a growth of cells that's thought to form from nerve cells in the walls of the digestive organs. The nerve cells play a part in the process that moves food through the body.

Small GISTs may cause no symptoms. And GISTs may grow so slowly that they don't cause problems at first. As a GIST grows, it can cause symptoms that may include belly pain and nausea.

GISTs can happen in people at any age, but they are most common in adults and very rare in children. The cause of most GISTs isn't known.

Symptoms

Gastrointestinal stromal tumor symptoms include:

  • A growth in the belly area.
  • Belly pain.
  • Fatigue.
  • Nausea and vomiting.
  • Not feeling hungry when you would expect to.
  • Feeling full if you eat only a small amount of food.
  • Dark-colored stools caused by bleeding in the digestive system.

When to see a doctor

Make an appointment with a doctor or other healthcare professional if you have any symptoms that worry you.

Causes

The cause of a gastrointestinal stromal tumor often isn't known. This cancer, which also is called a GIST, happens in the digestive system. It most often affects the stomach and small intestine. GISTs are thought to begin in nerve cells in the walls of the digestive organs. These nerve cells play a part in the process that moves food through the body.

A GIST starts when nerve cells in the digestive system develop changes in their DNA. A cell's DNA holds the instructions that tell the cell what to do. In healthy cells, the DNA gives instructions to grow and multiply at a set rate. The instructions tell the cells to die at a set time. In cancer cells, the DNA changes give different instructions. The changes tell the cancer cells to grow and multiply quickly. Cancer cells can keep living when healthy cells would die. This causes too many cells.

The cancer cells might form a mass called a tumor. The tumor can grow to invade and destroy healthy body tissue. In time, cancer cells can break away and spread. When cancer spreads, it's called metastatic cancer.

Risk factors

Risk factors for gastrointestinal stromal tumor, also called GIST, include:

  • Family history. People with a family history of GISTs may be at increased risk of this cancer.
  • Hereditary syndromes. People with some conditions that run in families may be more likely to have GISTs. Examples include neurofibromatosis type 1 and Carney-Stratakis syndrome.
  • Adult age. A GIST can happen at any age. This cancer happens most often in adults. It's rare in children.
By Mayo Clinic Staff