Gastrointestinal stromal tumors (GISTs) are tumors, or clusters of overgrown cells, in the gastrointestinal (GI) tract. Symptoms of GIST tumors include:

  • bloody stools
  • pain or discomfort in the abdomen
  • nausea and vomiting
  • bowel obstruction
  • a mass in the abdomen that you can feel
  • fatigue or feeling very tired
  • feeling very full after eating small amounts
  • pain or difficulty when swallowing

The GI tract is the system responsible for digesting and absorbing food and nutrients. It includes the esophagus, stomach, small intestine, and colon.

GISTs begin in special cells that are part of the autonomic nervous system. These cells are located in the wall of the GI tract, and they regulate muscle movement for digestion.

The majority of GISTs form in the stomach. Sometimes they form in the small intestine, but GISTs forming in the colon, esophagus, and rectum are much less common. GISTs can be either malignant and cancerous or benign and not cancerous.

Symptoms

The symptoms depend on the size of the tumor and where it’s located. Because of this, they often vary in severity and from one person to another. Symptoms such as abdominal pain, nausea, and fatigue overlap with many other conditions and diseases.

If you’re experiencing any of these or other abnormal symptoms, you should talk with your doctor. They will help determine the cause of your symptoms.

If you have any risk factors for GIST or any other condition that could cause these symptoms, be sure to mention that to your doctor.

Causes

The exact cause of GISTs isn’t known, although there seems to be a relation to a mutation in the expression of the KIT protein. Cancer develops when cells begin to grow out of control. As the cells continue to grow uncontrollably, they build up to form a mass called a tumor.

GISTs start in the GI tract and can grow outward into nearby structures or organs. They frequently spread to the liver and peritoneum (the membranous lining of the abdominal cavity) but rarely to nearby lymph nodes.

Risk factors

There are only a few known risk factors for GISTs:

Age

The most common age to develop a GIST is between 50 and 80. While GISTs can happen in people younger than 40, they’re extremely rare.

Genes

The majority of GISTs happen randomly and have no clear cause. However, some people are born with a genetic mutation that can lead to GISTs.

Some of the genes and conditions associated with GISTs include:

Neurofibromatosis 1: This genetic disorder, also called Von Recklinghausen’s disease (VRD), is caused by a defect in the NF1 gene. The condition can be passed from parent to child but isn’t always inherited. People with this condition are at an increased risk to develop benign tumors in nerves at an early age. These tumors can cause dark spots on the skin and freckling in the groin or underarms. This condition also increases the risk for developing a GIST.

Familial gastrointestinal stromal tumor syndrome: This syndrome is caused most often by an abnormal KIT gene passed from parent to child. This rare condition increases the risk of GISTs. These GISTs can form at a younger age than the general population. People with this condition can have multiple GISTs during their lifetime.

Mutations in the succinate dehydrogenase (SDH) genes: People who are born with mutations in the SDHB and SDHC genes are at an increased risk for developing GISTs. They’re also at increased risk for developing a type of nerve tumor called a paraganglioma.