About the gastrointestinal tract

The gastrointestinal (GI or digestive) tract includes the:

• Esophagus
• Stomach
• Gallbladder and bile ducts
• Liver
• Pancreas
• Small intestine
• Colon
• Rectum
• Anus
• Lining of the gut

The GI tract plays a central role in digesting food and liquid and in processing waste.  When you swallow food, it is pushed down a muscular tube called the esophagus and enters the stomach. The muscles in the stomach mix the food and release gastric juices that help break down and digest the food.

The food then moves into the small intestine, or small bowel, for further digestion before entering the large intestine. The large intestine helps remove waste from the body. The colon makes up the first 5 to 6 feet of the large intestine. The rectum makes up the last 6 inches, ending at the anus.

About gastrointestinal stromal tumor (GIST)

A tumor begins when healthy cells change and grow out of control, forming a mass called a tumor. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can grow and spread to other parts of the body. A benign tumor means the tumor can grow but will not spread. A tumor can start in any part of the GI tract. There are several different types of GI tumors, including gastrointestinal stromal tumor (GIST).

GISTs are different from more common types of GI tumors because of the type of tissue in which they start. GISTs belong to a group of cancers called soft-tissue sarcomas. Soft-tissue sarcomas develop in the tissues that support and connect the body. The sarcoma cells resemble the cells that hold the body together, including fat cells, muscles, nerves, tendons, joints, blood vessels, and lymph vessels.

Doctors used to think that GISTs were muscle or nerve tumors. However, research shows that GIST begins in “pacemaker” cells found in the walls of the GI tract. These pacemaker cells are called interstitial cells of Cajal (ICCs), and they send signals to the GI tract to help move food and liquid through the digestive system.

  

Symptoms :

People with GIST often do not experience any specific symptoms or signs. When symptoms do occur, they may be vague. Or, the cause of a symptom may be a different medical condition that is not a tumor.

• Pain or discomfort in the abdomen
• A mass in the abdomen that you can feel with your hand
• Bowel obstruction
• Nausea and vomiting
• Vomiting blood
• Blood in the stool
• Fatigue due to anemia, which is a low red blood cell count and is often caused by bleeding in the GI tract.

Stages:

For other types of GI tumors, the most common staging tool used is called the TNM system. TNM is an abbreviation for tumor (T), node (N), and metastasis (M). However, the use of the TNM system for GIST is not required. Instead, doctors look at different factors to determine a patient’s prognosis and the specific risk of how aggressive an individual tumor will be. Specifically, doctors want to figure out how quickly the GIST may grow and the chance the tumor will come back, or recur, after surgery.

Doctors commonly use the factors listed below to determine how aggressive a GIST that has been removed could be:

• The size of the tumor
• The mitotic count, which describes the number of dividing cells
• The location where the tumor started

A GIST that has spread to distant areas of the body is considered higher risk because it has a greater likelihood of coming back, called recurrent GIST.