Gastrointestinal Neuroendocrine Tumour

Gastrointestinal neuroendocrine tumours are rare cancers that form in special cells within the digestive system. While most grow very slowly, early diagnosis and proper treatment are essential for the best outcomes.

Table of contents

• What is a gastrointestinal neuroendocrine tumour?
• Associated anatomy
• Who is affected?
• Causes and risk factors
• Symptoms
• Carcinoid syndrome
• Diagnosis
• Treatment
• Prognosis and survival
• Living with gastrointestinal neuroendocrine tumours

What is a gastrointestinal neuroendocrine tumour?

A gastrointestinal neuroendocrine tumour (GI NET) is a type of cancer that forms in the lining of the gastrointestinal tract^[1]. These tumours are also called gastrointestinal carcinoid tumours^[1].

GI NETs develop from a special type of cell called a neuroendocrine cell. These cells are like a combination of nerve cells and hormone-making cells^[1]. They are scattered throughout your body, but most are found in the gastrointestinal tract^[1]. Neuroendocrine cells normally make hormones that help control digestive juices and the muscles used in moving food through the stomach and intestines^[1]. When a GI NET forms, it may also make hormones and release them into the body^[1].

GI NETs are rare cancers and most grow very slowly^[1]. They typically develop in the small intestine and rectum, but may also appear in the stomach, appendix, esophagus, or colon^[2][4]. Sometimes more than one tumour will form^[1].

These tumours can be categorized based on their characteristics. The degree of differentiation and grade are microscopic features that help predict how fast a cancer cell grows. Well-differentiated and low-grade tumours tend to grow more slowly, whereas poorly differentiated and high-grade tumours tend to grow more quickly^[4]. The stage refers to where the cancer has spread in the body^[4]. Functional status refers to whether a GI NET secretes hormones that can be measured in the blood or urine and cause symptoms^[4].

Associated anatomy

• Esophagus
• Stomach
• Small intestine
• Appendix
• Colon
• Rectum
• Liver (when tumours spread)

Who is affected?

GI NET affects about 4 in 100,000 people^[2]. Each year, approximately 8,000 adults in the United States are diagnosed with gastrointestinal neuroendocrine tumours^[2][4].

The condition typically affects people aged 55 to 65, but it can affect adults of any age^[2]. The average age at diagnosis is about 61 years^[3]. GI NET is more common in white people than in Black people^[2]. Women are slightly more likely to develop GI NET than men^[2].

While the incidence of GI NETs is low, the prevalence is quite high. This means many people are living with a NET due in part to the slow-growing nature of most NETs^[4].

Causes and risk factors

Medical researchers have not identified a specific cause of gastrointestinal neuroendocrine tumours^[2]. Anything that increases a person’s chance of getting a disease is called a risk factor. Not every person with one or more of these risk factors will develop GI NETs, and they can develop in people who don’t have any known risk factors^[1].

Risk factors for GI neuroendocrine tumours include having a family history of certain inherited conditions^[1]. These conditions include:

• Multiple endocrine neoplasia type 1 (MEN1) syndrome: A condition that causes certain glands to be overactive or form tumours^[1][2]
• Neurofibromatosis type 1 (NF1) syndrome: A rare condition where tumours grow on the skin and nerves^[1][2]
• Von Hippel-Lindau disease: A rare condition where benign tumours grow in various parts of the body^[2]
• Tuberous sclerosis complex^[4]

Having certain conditions that affect the stomach’s ability to make stomach acid can also increase risk. These include atrophic gastritis (a condition affecting the stomach lining), pernicious anemia (a blood condition), or Zollinger-Ellison syndrome (a condition that causes the stomach to make too much acid)^[1]. Researchers have also found links between GI NETs and low stomach acid^[2].

Symptoms

Some GI neuroendocrine tumours have no signs or symptoms in the early stages^[1]. Many people don’t experience any symptoms because these tumours are often slow-growing, sometimes forming over a period of months or years^[4]. Some people are diagnosed with GI NET because they had an imaging test to diagnose an unrelated condition^[2].

When people do have symptoms, they are similar to symptoms for less serious illnesses^[2]. Common GI NET symptoms include:

• Stomach pain: This could be a sign a GI NET has blocked your intestines^[2]
• Diarrhea: This symptom often affects people who have carcinoid syndrome or who’ve had their gallbladder or part of their intestines removed^[2]
• Nausea and vomiting: Persistent nausea and vomiting may be a symptom of serious illness^[2]
• Unintentional weight loss: Losing weight quickly without dieting or exercising is a common GI NET symptom^[2]
• Bright red blood in your stool or dark-colored, tarry stool: These symptoms might be signs you have intestinal bleeding^[2]
• Jaundice: This condition causes your skin and the whites of your eyes to turn yellow^[2]
• Fatigue: This symptom is more than feeling sleepy. Fatigue means you’re exhausted all the time^[2]

Carcinoid syndrome

Carcinoid syndrome is a group of symptoms that may occur if the tumour spreads to the liver or other parts of the body^[1]. This syndrome is characterized by systemic symptoms due to circulating tumour products^[3]. Some GI NETs are functional, producing bioactive hormones or peptides that can lead to specific clinical syndromes^[3].

People with carcinoid syndrome may experience:

• Reddening or flushing of the skin, particularly on the face^[4]
• Painful gas and bloating
• Severe diarrhea^[4]

Diagnosis

Diagnosis of GI neuroendocrine tumours often starts with a physical exam. A healthcare professional might check your body for signs of cancer and may feel for swollen lymph nodes or look for signs that a neuroendocrine tumour is producing excess hormones^[9].

Several types of tests are used to diagnose GI neuroendocrine tumours:

Blood and urine tests: Your healthcare professional may recommend testing your blood or urine for signs of extra hormones^[1][9]. Some people with NETs don’t have enough of a nutrient called niacin, which could cause dry, cracking skin around the mouth^[1].

Imaging tests: These tests make pictures of the inside of the body and can show the cancer’s location and size^[1][9]. Imaging tests might include:

• X-rays^[2]
• Ultrasound^[9]
• Computerized tomography (CT) scan^[9]
• Magnetic resonance imaging (MRI) scan^[9]
• Positron emission tomography (PET) scan with a special tracer. This kind of scan is sometimes called a somatostatin receptor PET scan or dotatate PET scan^[9]

Biopsy: A biopsy is a procedure to remove a sample of tissue for testing in a lab. In the lab, tests can show whether cancer cells are present^[9]. How a biopsy is done for a neuroendocrine tumour depends on where the cancer is in the body^[9].

Endoscopy: This procedure uses a tube with a camera to examine the inside of the digestive tract^[3].

Due to their usually slow-growing nature and nonspecific symptoms, GI NETs are frequently diagnosed late, with spread to other areas present in many cases^[3].

Treatment

Treatment of gastrointestinal neuroendocrine tumours depends on various factors, including the type of tumour, its location, whether it produces excess hormones, how aggressive it is, and whether it has spread to other parts of the body^[9]. The specific characteristics of each tumour influence its management^[3].

Surgery: The most common treatment is surgery to remove the tumour^[2]. Surgical resection remains the primary treatment when feasible^[3].

Watchful waiting: For some very small or slow-growing tumours, doctors may recommend careful monitoring without immediate treatment^[4].

Liver-directed therapy: When tumours have spread to the liver, special treatments that target the liver may be used^[4].

Radiation therapy: This treatment uses high-energy rays to destroy cancer cells^[4].

Chemotherapy: This treatment uses drugs to kill cancer cells or stop them from growing^[4].

Hormone therapy: Some treatments use hormones or hormone-blocking drugs to help control the disease^[4].

Targeted therapy: These are newer treatments that target specific features of cancer cells^[4].

Management approaches may include nonsurgical and surgical therapies^[3]. The treatment plan will be tailored to each individual patient based on their specific situation.

Prognosis and survival

The outlook for people with gastrointestinal neuroendocrine tumours varies significantly depending on several factors. These include the stage and primary site of the tumour^[4].

According to recent analyses, the five-year overall survival for all stages combined is about 81%^[1]. Around 94% of people with gastrointestinal NETs survive five or more years after diagnosis^[4].

The likely outlook varies depending on the type and how well the person is^[1]. Some neuroendocrine cancers grow quicker than others, and some are more likely to come back than others. However, many are curable or can be controlled for many years^[1].

Not everyone wants to know about their prognosis. It’s okay if you don’t want to read survival information. The best person to discuss your likely prognosis is your doctor. Talk to them or to your specialist nurse if you want to know more^[1].

Living with gastrointestinal neuroendocrine tumours

Diet and nutrition

Neuroendocrine tumours and their treatments can affect your diet and digestion. This might influence your body’s ability to extract adequate nutrients from food, depending on the type of tumours you have and the treatment you are receiving^[19].

If you have carcinoid syndrome, you may find that some kinds of foods and drinks trigger problems. It may help to avoid foods high in amines, compounds that affect blood pressure or body temperature. These include aged or blue cheeses, chocolate, red wine, beer, smoked meats like salami or sausage, pickled fish like herring, and fermented foods^[23].

Some dietary tips that may help ease symptoms include eating smaller, frequent meals, avoiding fatty, greasy, or highly spicy foods, and choosing whole, natural foods over processed ones high in salt^[23]. Eating healthy foods can keep your strength and energy up while you get treatment^[23].

If you have been given specific dietary advice by a qualified healthcare professional such as a dietician, specialist nurse, or doctor, then follow that advice as it will be tailored to you^[22]. Seek advice from a qualified healthcare professional specializing in NETs if you are losing weight or are severely restricting your diet^[22].

Exercise and lifestyle

A healthy lifestyle can help you feel better in general. Keep up with exercise, such as taking a half-hour walk, three times a week or more^[23]. If you smoke, it’s important to quit^[23].

Taking a multivitamin may help if recommended by your doctor. Some people with NETs don’t have enough niacin, and a balanced diet or vitamin supplement may help^[23].

Emotional support

It’s natural to feel anxious, stressed out, and sometimes depressed when you find out you have a NET. If you don’t take care of your emotional needs, it can make it harder to treat your tumour^[23].

You might have a number of different feelings, such as feeling shocked, upset, numb, frightened and uncertain, confused, angry and resentful, guilty, or sad^[21]. You may have some or all of these feelings, or you might feel totally different. Everyone reacts in their own way^[21].

It can help a lot to set up a support network you can rely on. You might benefit from going to a support group for people who have NETs^[23]. Talking to your friends and relatives about your cancer can help and support you^[21]. You might find it easier to talk to someone other than your own friends and family, and you may want to see a counsellor^[21].

Meditation helps some people manage stress. Talk to your doctor if you need help dealing with it^[23].

Keeping track of your care

It might help to make lists, have a calendar with all appointments, set goals, and plan enjoyable things around weeks that might be emotionally difficult^[21]. Remember that you don’t have to sort everything out at once. It might take some time to deal with each issue. Ask for help if you need it^[21].