Small Intestine Neuroendocrine Tumour

Small intestine neuroendocrine tumours are rare cancers that develop in special hormone-making cells of the small bowel. While uncommon, they are one of the most frequent types of cancer found in the small intestine, and many people live with them for years with proper care and treatment.

Table of contents

• What are small intestine neuroendocrine tumours?
• The small intestine and its parts
• How common are these tumours?
• Risk factors
• Symptoms
• Carcinoid syndrome
• How doctors diagnose these tumours
• Treatment options
• Living with small intestine neuroendocrine tumours

What are small intestine neuroendocrine tumours?

Small intestine neuroendocrine tumours are a type of rare cancer that starts in neuroendocrine cells (cells that work like both nerve cells and hormone-making cells) in the small bowel^[1]. These cells are scattered throughout the body and make hormones that help control how our bodies work^[4].

The digestive system has more neuroendocrine cells than any other part of the body^[1]. In the small intestine, these cells help control digestive juices and the muscles that move food through the stomach and intestines^[4].

These tumours belong to a larger group of cancers called neuroendocrine neoplasms (NENs). There are two main types: neuroendocrine tumours (NETs), which tend to grow slowly, and neuroendocrine carcinomas (NECs), which usually grow much faster^[1]. It is very important to know which type you have, as this affects your treatment and outlook.

Historically, these tumours were called “carcinoid tumours.” The name was first used over a century ago to describe unusual tumours in the small intestine that behaved differently from typical bowel cancers^[2]. Today, doctors prefer the term neuroendocrine tumour because it more accurately describes what these cancers are^[10].

The small intestine and its parts

The small bowel is part of the digestive system. It makes up most of the digestive tract and is about 6 metres long, but it is folded up so that it fits inside the abdomen^[1].

The small intestine has three sections^[1]:

• The duodenum is just beyond the lower part of the stomach and connects the small bowel to the stomach
• The jejunum is the middle part
• The ileum is the lower part, which connects to the large bowel (colon)

Most small intestine neuroendocrine tumours develop in the ileum and jejunum^[1]. The tumours are typically located in the terminal ileum and often appear as flat, hardened growths under the lining of the bowel, commonly measuring 1 centimetre or less^[2].

• Small intestine (small bowel)
• Duodenum
• Jejunum
• Ileum

How common are these tumours?

Small intestine neuroendocrine tumours are rare. Around 610 people are diagnosed with a small bowel neuroendocrine cancer every year in England^[1]. In the United States, about 8,000 adults are diagnosed with gastrointestinal neuroendocrine tumours each year, with many of these occurring in the small intestine^[5].

Although rare overall, small intestine neuroendocrine tumours are now the most common type of cancer that starts in the small intestine^[10]. Around 40 out of 100 (around 40%) of small bowel cancers are neuroendocrine cancers^[1].

The condition typically affects people aged 55 to 65, but it can affect adults of any age^[5]. The number of people being diagnosed with small intestine neuroendocrine tumours is increasing^[10]. This may be partly because doctors are getting better at finding them as diagnostic techniques improve^[3].

Risk factors

A risk factor is anything that increases your risk of getting a disease. At the moment, there are no clear risk factors for small bowel neuroendocrine cancer^[1].

Having a family history of cancer is a risk factor for all types of neuroendocrine cancer, including small bowel neuroendocrine cancers^[1]. Rarely, more than one person in a family develops a small bowel neuroendocrine tumour, although it is more common for this not to happen^[1].

People with certain inherited conditions may develop gastrointestinal neuroendocrine tumours. These conditions include^[4][5]:

• Multiple endocrine neoplasia type 1 (MEN1) syndrome, which causes certain glands to be overactive or form tumours
• Neurofibromatosis type 1 (NF1), a condition where tumours grow on the skin and nerves
• Von Hippel-Lindau disease, a rare condition where non-cancerous tumours grow in various parts of the body

Some people with a small bowel neuroendocrine tumour develop another small bowel neuroendocrine tumour in the future^[1].

Symptoms

Not everyone with a small bowel neuroendocrine cancer has symptoms. Doctors often diagnose a small bowel neuroendocrine cancer when looking for something else. For example, a doctor might see the cancer on a CT scan which you have for another reason^[1].

If you do have symptoms, they might be vague and similar to other conditions that aren’t caused by cancer. The vague presentation and slow growth of these tumours lead to long delays in diagnosis, and many patients present with tumours that have already spread (metastases)^[10].

Symptoms of small intestine neuroendocrine tumours might include^[1][3]:

• Tummy (abdominal) pain that doesn’t go away
• Weight loss without trying
• Changes to your bowel movements, such as diarrhoea
• Bleeding in your digestive system, which might cause your poo to be black or blood in your vomit
• Feeling or being sick
• Feeling very tired all the time
• Bowel obstruction, causing severe abdominal pain, vomiting, and constipation

These symptoms occur because of the growth of the cancer in your small intestine or in nearby lymph nodes, the cancer spreading to other parts of the body, or hormones made by the cancer^[1].

The tumours may be accompanied by enlarged growths in the mesentery (the tissue that anchors the intestine). These enlarged areas are often conspicuously larger than the original tumour and are typically associated with marked hardening and scarring^[2]. This scarring can trap loops of the small intestine and cause partial or complete intestinal blockage^[2].

It’s important to get these symptoms checked out by your doctor, even though they can also be caused by other medical conditions^[1].

Carcinoid syndrome

Some small bowel neuroendocrine cancers make hormones that go into the bloodstream. Doctors call these “functioning tumours”^[11].

When a neuroendocrine tumour releases large amounts of hormones into the blood, it can cause a group of symptoms called carcinoid syndrome^[2]. Small intestinal neuroendocrine tumours represent the most common (90%) cause of carcinoid syndrome^[2].

The carcinoid syndrome consists of^[2][3]:

• Diarrhoea
• Flushing (redness and warmth of the face and neck)
• Wheezing or difficulty breathing
• Heart problems (carcinoid heart disease)

These symptoms are attributed to various substances released from the tumours, including serotonin and other chemicals^[2].

Presence of the syndrome generally means that the patient has tumours that have spread to the liver (liver metastases). Only occasionally is it encountered when veins from tumours in other locations drain directly into the general blood circulation^[2].

How doctors diagnose these tumours

Diagnosing small intestine neuroendocrine tumours requires a combination of tests. Your doctor will use imaging studies and tests that examine the blood and urine^[4].

Diagnostic tests may include^[5][8]:

• Blood tests to look for tumour markers and hormone levels
• Urine tests to measure substances released by the tumours
• Imaging tests such as CT scans, MRI scans, or specialised nuclear medicine scans that can detect neuroendocrine tumours
• Endoscopy, where a thin tube with a camera is used to look inside your digestive system
• Biopsy, where a small sample of tissue is taken and examined under a microscope

Sometimes doctors discover these tumours during surgery for other reasons or during examinations for unrelated conditions^[1].

Treatment options

The treatment you have depends on what type of neuroendocrine cancer you have, where it is located in your small bowel, whether it has spread (stage), how fast the cells are growing (the grade), the symptoms you have, and your general health and fitness^[11].

A team of doctors and other professionals, called a neuroendocrine multidisciplinary team, discusses the best treatment and care for you^[11].

Surgery

Surgery is the main treatment for small bowel neuroendocrine cancers^[11]. Surgery might be all the treatment you need if your cancer hasn’t spread^[11].

The type of operation you have depends on where the cancer is in your small bowel, the size of your cancer, and how fast it is growing^[11]. Surgery may involve removing the affected section of the small intestine along with nearby lymph nodes and areas of scarring in the mesentery^[2].

Even when tumours have spread to the liver, surgery to remove intestinal and mesenteric tumours may be done to prevent abdominal complications^[2]. Removing liver tumours may also help with treatment of carcinoid syndrome^[2].

Medical treatments for NETs

If surgery isn’t possible, or in addition to surgery, other treatments for small bowel NETs include^[11]:

• Somatostatin analogues, which are medications that can block the growth hormones that feed these slow-developing tumours and help control symptoms of carcinoid syndrome^[2]
• Chemotherapy, which uses drugs to kill cancer cells
• Targeted cancer drugs, which work by targeting specific features of cancer cells
• Peptide receptor radionuclide therapy (PRRT), a specialised treatment that combines a targeting molecule with a radioactive particle to destroy cancer cells^[11]
• Interferon, which may help control symptoms^[2]

Some treatments focus on managing symptoms and improving quality of life rather than curing the disease. Patients with small bowel neuroendocrine tumours that have spread often have a favourable outlook compared to other gastrointestinal cancers and benefit from aggressive, multimodal therapy^[10].

Treatments if cancer has spread

If the cancer has spread to the liver, you might have^[11]:

• Surgery to remove liver tumours
• Other treatments directed at the liver

Living with small intestine neuroendocrine tumours

Living with a small intestine neuroendocrine tumour can be challenging. Because these tumours often grow slowly, many people live with them for years^[10]. This means learning to manage a chronic condition.

Emotional wellbeing

You might have a number of different feelings when you’re told you have cancer. You may feel shocked, upset, frightened, uncertain, confused, angry, guilty, or sad^[18]. You may have some or all of these feelings, or you might feel them a few at a time or altogether, leaving you feeling exhausted^[18].

Everyone reacts in their own way. You need to do what’s right for you to help you cope^[18]. Talking to your friends and relatives about your cancer can help and support you, though some people find this difficult^[18]. You might find it easier to talk to someone other than your own friends and family, such as a counsellor or support group^[18].

Ongoing care and monitoring

If you have a small intestine neuroendocrine tumour, you will likely need regular check-ups with your healthcare team. These appointments help your doctors monitor your condition and adjust treatment as needed.

You are likely to have a clinical nurse specialist who can help answer your questions and support you throughout your treatment. They can be your main point of contact^[11].

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 that you have and treatment you are receiving or any previous surgeries that you have had^[21].

Certain foods or eating habits may trigger common symptoms related to neuroendocrine tumours^[21]. Diet and nutrition play an important role in helping to reduce symptoms, ensure a balanced diet, increase your quality of life, and improve your response to treatment by ensuring you stay well nourished^[21].

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^[21].

Staying active

Many people with small intestine neuroendocrine tumours continue to stay active and engaged in their daily lives. Some continue to work, exercise, travel, and enjoy hobbies despite their diagnosis^[23].

Getting support and information

You may be more able to cope and make decisions if you have information about your type of cancer and its treatment^[18]. Information helps you to know what to expect.

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^[18].

Patient support groups for neuroendocrine tumours can provide social and emotional support^[3]. Connecting with others who have similar experiences can be very helpful.