The small bowel (or small intestine) is the longest part of the digestive system. It is only about as wide around as a middle finger (approximately 1 inch or 2.5cms) and is, on average, 600cms in length in an adult (we need at least 200cms to maintain normal function). It’s major function is to absorb food and nutrients and so it has a lining with many folds that increase the surface area of the small intestine – allowing for better absorption if nutrients.
It can be divided into 4 parts:
- Duodenum – first and shortest part, joins stomach to rest of small bowel, in an almost C shaped curve as it passes the head of the pancreas. Bile drains into it from the liver (via gall bladder) and digestive enzymes from the pancreas also drain into this part to further digest (breakdown) food to allow for better absorption of nutrients. Iron is also absorbed at this point.
- Jejunum – second part, most nutrients from food continue to be digested and are absorbed here.
- Ileum – third and longest part, any residual nutrients and B12 are absorbed here.
- Terminal ileum and ileo-caecal valve or junction – where the large and small bowel meet – here bile salts are reabsorbed to be returned to the liver to continue producing good quality bile.
The small bowel is anchored within the abdomen by a double fold of peritoneum (lining of the abdomen) called the mesentery. Lymph nodes and the blood supply to the intestines run through it.
It is not uncommon for Neuroendocrine of the Small Bowel to be diagnosed because of symptoms related to or scans showing an enlarged lump of lymph nodes or ‘mass’ within the mesentery or ‘mesenteric fibrosis”. The primary tumour itself may be too small to be visible.
In Mesenteric Fibrosis – fibrotic strands form between tissues and organs of the small bowel and mesentery, like internal scar tissue, they connect tissues not normally connected – causing ‘gathering’ or kinking. This fibrotic process, thought to be related to the presence of a tumour and/or excess serotonin production, can entrap loops of the small intestine and cause partial or complete intestinal obstruction.
Causes and potential risk factors for Neuroendocrine Cancer
We do not know exactly what causes Neuroendocrine Cancer – however it is important to follow advice in leading a healthy lifestyle: eat healthily, exercise and avoid smoking and too much alcohol.
Most Neuroendocrine Cancers do not run in families; however, a number of rare conditions may increase the risk of them developing. Therefore, if other members of the family have been diagnosed with cancer, or have a known genetic condition, it is important that you tell your specialist team about not only your personal medical history, but also any family medical illnesses or conditions.
Having a family history of bowel cancer in a first-degree relative – a mother, father, brother or sister –under the age of 50 or 2 or more close relatives diagnosed with bowel cancer at any age (for example your parent, and their sibling or parent) can increase your lifetime risk of bowel cancer.
However, less than 10% of ALL bowel cancer cases are thought to be caused by a change in a known gene.
The known genetic conditions linked to bowel cancer include Lynch syndrome, FAP (Familial Adenomatous Polyposis) and MAP (MUTYH Associated Polyposis).
There is no identified link with Neuroendocrine Cancer of the Bowel (large or small), but up to 30% may have a more common bowel cancer occur – either at the same time or before/after a diagnosis of Neuroendocrine Cancer of the Bowel is made.
We recommend speaking to your GP, and specialist team, if bowel cancer runs in your family (as above). They may refer you for an NHS genetic test, which will tell you if you have inherited one of the cancer-risk genes.
So whilst there is no known genetic condition linked with Small Bowel Neuroendocrine Cancer – if you have a risk of bowel cancer – this is important information for you and your team to know – as it may play a role in how your care and follow up is discussed, planned and agreed.
Symptoms that may or may not include Neuroendocrine Cancer associated syndromes
(A syndrome is 2 or more associated symptoms)
Small Bowel Neuroendocrine Cancer, in early stage disease, can be a very silent disease – in that symptoms may not be present, however, if symptoms do occur, they may be due to size and position of the cancer – and how it is growing:
They may be acute (sudden and severe) – for example; signs of bowel obstruction – increasingly severe abdominal pain/cramping associated with vomiting.
Or chronic (occur over time and change in severity and frequency) – for example may be similar to symptoms of Irritable Bowel Disease – abdominal discomfort/cramping, diarrhoea, bloating, altered bowel habit.
Although Carcinoid Syndrome may also occur at this point, it is more commonly associated with disease that has spread (metastasised) to the liver – symptoms include:
- ‘Dry’ flushing : a red ‘blush’ of the face, neck and chest (which can extend over the whole body), and may be associated with pins & needles in hands and feet, headache and / or palpitations (fast-beating, fluttering or pounding heart)
- Diarrhoea : watery, loose stools multiple times a day—sometimes associated with considerable urgency – that may be more urgent/frequent in early hours to mid morning
- Carcinoid / valvular heart disease
- Wheezing (bronchospasm) and / or shortness of breath
- And/or skin changes
The syndrome is caused by the Neuroendocrine Cancer: the abnormal neuroendocrine cells within it, can release higher than normal levels of the peptides and hormones they would normally produce – causing altered function, leading to the symptoms described above.
Later symptoms may include scaly, irritated skin (caused by a lack of the vitamin B3 – niacin), arthritis, muscular weakness (myopathy), and symptoms related to secondaries in the liver and / or Carcinoid Heart Disease.
Further information on Carcinoid Heart Disease and Neuroendocrine Cancer Associated Syndromes is available here.
Tests that may be used for the diagnosis and / or monitoring of Neuroendocrine Cancer of the Small Bowel.
Bloods and / or urine:
Full blood count
B12 + serum Iron
Liver and kidney function
Chromogranin A (and B)
Full Gut Hormone Profile
NT-Pro-BNP – to check for evidence of Carcinoid Heart Disease
Vitamin and trace element/mineral check alongside formal dietetic assessment is advised at baseline and as clinically indicated in follow up : Vitamin D, B3 & B12 deficiency and evidence of early malnutrition in symptomatic patients is not uncommon.
Scans and other tests:
Echocardiogram : as a baseline in the presence of carcinoid syndrome / raised U5HiAA and / or elevated NT-Pro-BNP +/- clinical signs of heart valve impairment/R sided heart failure
Colonoscopy : may be useful in detecting distal ileal disease and for excluding other colorectal abnormalities
VCE – video capsule endoscopy –
CT thorax/abdo/pelvis or MRI abdo/pelvis + CT chest
CT enterolysis (a CT examination of the small bowel)
Gallium-Dotatate PET/CT (SRS SPECT/CT if Dotatate PET n/a)
FDG-PET – if High Grade / rapidly progressing disease
Pathology (what can be seen through special tests under a microscope):
Differentiation and cellular morphology
cdx-2, p53 and / or SSTR 2a (optional)
The key aim of treatment, should be to help you have the best possible care and quality of life – by ensuring access to appropriate treatment, management of symptoms and addressing what’s most important to you
Treatment options will depend on the type, position and size of your cancer – and whether (and to where) it has spread.
It will also depend on whether you have any other health concerns and / or illnesses and your general health and fitness.
One or more of the approaches below may be suggested:
- Control of your disease, by slowing or stopping further growth and / or spread
- Palliation, or easing, of any symptoms you may be experiencing.
Monitoring through clinic review, bloods and scans, can be used to assess how well treatment is working or in periods between treatments (which may be months/years).
As not everyone will need to be on treatment – surveillance can be used to check your cancer and general health for any signs of change that may mean that a treatment might need to be considered. All treatments have possible side-effects, therefore, it is important to know when treatment may be helpful for you or not.
To remove, partially remove or bypass neuroendocrine cancer and / or secondary sites of disease (metastases). Careful clinical and radiological (review of scans) assessment is required in planning surgery of the small bowel due to the complexity of the mesentery –
- Blood supply to remaining bowel needs to be maintained
- Assessment of how much small bowel will need to be resected to remove cancer but maintain function.
Small bowel segmental resection:
Removal a specific segment of the small bowel
Ileo-caecal valve resection:
Terminal ileum, ileo-caecal valve and part of the right colon is removed.
Ileocaecal valve resection plus right hemicolectomy:
Terminal ileum, ileo-caecal valve and all of the right colon is removed.
+/- Mesenteric mass / lymph node resection : removal of mesenteric mass and / or lymph nodes associated with mesenteric mass and / or primary tumour.
Somatostatin analogues (SSAs):
Can be used to help regulate the secretion of hormones if abnormal levels are being produced. SSAs may also be used to slow down growth rate in low to moderate grade ‘well-differentiated’ neuroendocrine cancer (NET).
Can be given orally (in tablets) or Intravenously (through a vein) to slow tumour growth or try to reduce tumour size. This may be the first line therapy in high grade disease – particularly “poorly-differentiated’ NEC or in combination with other treatments. Chemotherapy may also be used to increase tumour cell sensitivity to radiation therapies.
Targeted Molecular Therapies:
Can be given orally (in tablets) or Intravenously (through a vein) to slow tumour growth or try to reduce tumour size.
Peptide receptor radionuclide therapy (PRRT):
May also be called Radioligand Therapy – uses targeted radiation to treat neuroendocrine cancer cells. Can be used in some patients who have had a ‘positive’ Octeotide or Gallium scan (‘receptor positive’ disease).
Treatment given via endoscopy – for example, removal of a stomach, bowel or rectal polyp.
Through techniques such as embolisation or ablation – can be used to treat Neuroendocrine Cancer that may develop in the the liver and / or lung(s).
Clinical research and safe new treatment development is essential to provide best care for those with Neuroendocrine Cancer – we need to know that treatments not only work but work safely. There are several phases of trial therapy – further information can be found here.
Each trial will have specific criteria in regards to patient suitability – this can be discussed with your clinical team. You do not have take part in a trial – participation is voluntary.
Managing symptoms, including pain and diarrhoea, is an important part of total care – and therefore occurs throughout care, not just at ‘end-of-life’. Symptom control or ‘palliation’ refers to what is used to alleviate or reduce the impact your cancer, other health issues and /or treatments may be having on you and your physical and mental health. It can include anything from simple medication and / or a combination of some of the treatments mentioned above to counselling and practical support.
There are expert agreed guidelines regarding how and when follow up should occur, however, in practice this varies and often with good reason – follow up should be expert informed & evidence /research based but also tailored to you and what is appropriate for your best care.
Grade 1 or 2:
- Surgery undertaken with curative intent: 6-12 monthly CT* + bloods and urine
- Non-curative surgery / residual disease: 3-6monthly CT* + bloods and urine.
Grade 3a and b:
- 3 monthly CT* + bloods and urine
CT*: Chest, abdomen and pelvis
If long term can replace CT abdomen/pelvis with MRI abdomen/pelvis but will need to continue CT chest.
If recurrence / progression suspected.
- Grade 1-3a : Gallium-Dotatate PET/CT (SRS SPECT/CT if Dotatate PET n/a)
- Grade 3a and b : FDG-PET – if High Grade / rapidly progressing disease
Inoperable disease: as per non-curative protocol. N.B. high lifelong risk of sub-acute/acute small bowel obstruction and / or ischaemia.
Consensus guidelines recommend lifelong surveillance.
Nutritional assessment and ongoing monitoring, as clinically indicated, is also advised.
Follow up as per guidelines – but should be guided by prognosis, expected treatment efficacy and treatment related toxicity.
Your health, well-being, physical activity, informed choice and preference for ongoing care as well as aim of treatment should be reviewed and discussed to best plan care.
Neuroendocrine Cancer UK is a UK wide charity solely dedicated to providing support and information to those affected by Neuroendocrine Cancer.
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