Symptoms of Gastrointestinal Stromal Tumors & Gastric Neuroendocrine Tumors

Gastrointestinal stromal tumors (GISTs) and gastric neuroendocrine tumors (NETs) are two uncommon types of stomach (gastric) cancer.

GISTs can occur anywhere along the gastrointestinal (GI) tract, but most begin in the stomach and small intestine. These tumors originate from specialized cells called the interstitial cells of Cajal (ICCs), found in the muscularis propria layer of the GI wall. Known as the ‘pacemaker’ cells of the gut, ICCs are responsible for sending signals to trigger muscular contractions that move stomach food and liquid along the digestive tract (peristalsis).

On the other hand, gastric NETs originate from a type of neuroendocrine cell called enterochromaffin-like (ECL) cells in the mucosal lining of the stomach. These specialized cells produce hormones controlling the release of gastric juices and how quickly food moves through the stomach.

Smaller, early-stage GISTs and gastric NETs usually do not give rise to any symptoms. In fact, such tumors are often discovered incidentally during tests and scans for other medical conditions, such as abdominal problems and indigestion. However, advanced GISTs and NETs that are larger and fast-growing can cause a wide range of non-specific symptoms.

Abdominal pain

A commonly reported symptom of GISTs and gastric NETs is pain or discomfort in the abdomen. This happens when the mechanical pressure caused by the growth of a large tumor pushes into the stomach’s mucosal wall. This can create holes or perforations and/or activate pain receptors in the GI tract, which may trigger a visceral pain sensation and abdominal discomfort.

Severe abdominal pain is often observed in metastatic GISTs, which tend to be fragile and can rupture easily. In these cases, immediate surgery may be required.

Anemia and fatigue

Because GISTs are fragile tumors, they are more likely to rupture and bleed. The loss of blood from a slow-bleeding GIST, known as GI bleeding, can lead to a low red blood cell (RBC) count. This condition is called anemia. Because your RBCs are responsible for delivering oxygen to the tissues in your body, having anemia can make you feel breathless, tired and weak. When this persists, chronic anemia can cause extreme and constant lethargy, known as fatigue. GI bleeding is a rare manifestation in people with gastric NETs. However, if it does occur, it can also lead to anemia and fatigue.

Appetite changes and weight loss

If a large tumor or numerous tumors are growing in the stomach, the lack of space available for the stomach to expand during digestion may limit the amount of food that can be processed at any given time. For this reason, eating even a small amount of food can make you feel bloated or full very quickly (early satiety). This may lead to appetite changes and subsequent weight loss, especially if you also experience nausea, vomiting and abdominal pain when eating.

Nausea and vomiting

The mechanical pressure caused by tumor growth or the accumulation of blood from a bleeding GIST or gastric NET can push into nerve endings located in the stomach. The irritation of these nerve endings, which send messages that stimulate the parts of the brain controlling nausea and vomiting, can aggravate these symptoms.

If left to persist, these symptoms can lead to more serious health problems, such as malnutrition and dehydration. Therefore, seek medical attention if you’re experiencing prolonged bouts of nausea and vomiting. Your doctors may prescribe medication to help keep food and fluids down.

Blood in stools or vomit

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GISTs are fragile tumors that tend to bleed easily. As the tumor develops, it puts pressure on the mucosal wall of the stomach. This can create holes in the GI tract and cause nearby blood vessels to burst, which leads to GI bleeding.

Rapid bleeding from stomach tumors can cause blood to appear in your stools, which will typically look black and tarry. This black and tarry feces associated with GI bleeding is usually referred to as melena. It occurs due to the blood changing color from red to black as it takes a longer time to leave the GI tract. GI bleeding can also make you throw up blood, which might look like ground-up coffee beans in your vomit due to partial digestion.

GI bleeding is rare in people with gastric NETs. However, bloody stools or blood in vomit are not uncommon when there is rapid bleeding from a gastric tumor into the GI tract.

Carcinoid syndrome

In some rare instances, gastric NETs that have spread to the liver can give rise to symptoms such as flushing and swelling. This collection of symptoms, triggered by the release of various hormones, is known as carcinoid syndrome. The carcinoid syndrome resulting from metastatic gastric NETs is considered atypical. This is because its symptoms vary from those usually caused by metastatic NETs of midgut (small intestine, appendix and proximal colon) origin.

> Learn more about carcinoid syndrome and other syndromes associated with gastric NETs

GISTs and NETs can cause a range of unpleasant and discomforting symptoms. These symptoms may require medical intervention to manage. It is crucial for patients to rely on their cancer care team for guidance and support throughout their journey. Your care team will provide you with all the necessary information to help you manage the challenges of this disease.