Supporting the

Neuroendocrine Cancer Community



Neuroendocrine Neoplasm (NENs) is an umbrella term used to cover a group of cancers that start in neuroendocrine cells. These cancers may also be referred to as NETs, NECs, or even Carcinoids. NENs occur when neuroendocrine cells stop working normally and start to grow or behave abnormally.

There are 2 key types of NEN:

  1. NETs (neuroendocrine tumours) are called ‘well-differentiated’ and may be Grade 1, 2 or 3 (slow to rapid growth rate).
  2. NECs (neuroendocrine carcinomas) – are called ‘poorly differentiated’ and are usually Grade 3 (rapid growth rate.


    To simplify, we use the term NENs throughout this page.

Large Bowel NEN


The large bowel is also known as the large intestine or colon. It forms the last part of the digestive system leading to the rectum. As food passes through the digestive system it is broken down and the nutrients we need to survive are extracted. By the time it reaches the colon it is mostly fluid and waste product. Bacteria in the colon breaks down any remaining substances and water is absorbed – whatever remains passes into the rectum to be excreted as waste (‘stool’).

Bloating, gas and pain may be experienced if the colon isn’t working properly; diarrhoea and, or constipation can occur. Irritation of the lining of the colon or damage such as a tumour forming can lead to bleeding which may appear in the stools, as blood, or the stool may be black and tarry.

NENs of the Large Bowel can be NETs or NECs. Sometimes NENs can occur in combination with the more common Large Bowel (Colon) Cancer, either as completely separate cancers within the large bowel or as one cancer containing both kinds of cancer cell, this is called MiNEN (mixed Neuroendocrine nonNeuroendocrine Neoplasm).


Not all cancers are the same or behave in the same way. Some may grow very slowly, may not have invaded nearby structures, or spread to other parts of the body at the time of diagnosis – but they have the potential to. However some may have already spread at the time of diagnosis.

The grade is the rate at which the NEN grows. You might see this referred to as ‘Ki67’ or ‘Mitotic Index’ mentioned in your clinic letters or medical reports. Grade 1 is slow-growing through to Grade 3, a more aggressive, rapidly growing disease.

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 developing the condition yourself.

Less than 10% of ALL bowel cancer cases are thought to be caused by a change in a known gene.

The genetic conditions include Lynch syndrome, FAP (Familial Adenomatous Polyposis) and MAP (MUTYH Associated Polyposis).

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.

Neuroendocrine Cancer of the Large Bowel is rare – and may not be associated with the above mentioned genetic alterations or family history. However, if you do have a genetic alteration or strong family history of Bowel/Colorectal or Neuroendocrine Cancer – knowing this information may help your specialist team in planning your care and ensuring follow up is appropriate for you.

Symptoms that may or may not include Neuroendocrine Cancer associated syndromes
(Syndrome is where 2 or more related symptoms occur).

Symptoms of Neuroendocrine Cancer of the Colon may be very similar to those that occur in Bowel Cancer, and include:

  • A persistent change in your bowel habits, including diarrhoea or constipation or a change in the consistency of your stool
  • Rectal bleeding or blood in your stool (may make it look black / tar-like)
  • Persistent abdominal discomfort, such as bloating, cramps, gas or pain
  • A feeling that your bowel doesn’t empty completely
  • Weakness or fatigue
  • Unexplained weight loss

However, many people experience no symptoms in the early stages of the disease. When symptoms appear, they may be related to the cancer’s size and location.

They are not usually associated with a Neuroendocrine associated syndrome – those that may produce Carcinoid Syndrome are more commonly found in the ascending colon (the first part of the large bowel) or where Neuroendocrine Cancer may have spread to the liver.

Other, rarer symptoms, including Paraneoplastic syndrome and oncological emergencies, (a specific set of health concerns that can occur in any cancer), such as raised calcium levels (Hypercalcaemia), may occur.

Further information about Neuroendocrine Cancer associated and Paraneoplastic Syndromes – including Oncological emergencies – can be found here.

Tests that may be used for the diagnosis and / or monitoring of Neuroendocrine Cancer of the Large Bowel:

Blood and / or urine:

Full blood count
Liver and kidney function
Chromogranin A
Urinary or serum 5HiAA (serotonin).


CT chest, abdomen and pelvis and/ or CT chest & MRI abdomen and pelvis
Octreotide (SPECT) or Gallium-Dotatate PET/CT


Colonoscopy +/- biopsy

Pathology (what can be seen through special tests under a microscope):

Differentiation and cellular morphology
Low molecular weight keratins

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:

  • Surgery
  • 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.

May be offered to remove the part of the colon that contains the cancer and the nearby lymph nodes, then where possible rejoins the non-tumour part of the bowel back together (the join is called an anastomosis) Surgery to remove part of the colon is called a colectomy – there are several types of colectomy:

Right hemi-colectomy:
Removes the ascending colon +/- ileo-caecal valve.

Extended R hemi-colectomy:
Removes ascending and transverse colon

L hemi-colectomy:
Removes the descending colon

Hartmans procedure:
Sigmoid colon and top part of the rectum and may require a temporary stoma*

Sub-total colectomy:
Removes all of the colon apart from the rectum and anus

Removes the whole colon and rectum

Removes the whole colon, rectum and anus – requiring a permanent stoma*

If the cancer is very small (or contained within a polyp) – local resection may be offered – through either surgery or colonoscopy.

Surgery may also be offered to relieve symptoms of or bypass cancer than can not be removed.

*A stoma is formed by bringing part of your colon (large bowel) or the end or loop of ileum (small bowel) out on to the surface of your abdomen – and may be temporary or permanent depending on how much bowel you have left or how healthy your remaining bowel is. Waste passes out of the stoma and is collected in an external pouch (known as a stoma bag).

A large bowel stoma is called a colostomy and a small bowel stoma is called an ileostomy. Waste from an ileostomy is usually more liquid than from a colostomy as it leaves the body before passing through the colon (where water is often reabsorbed).

Non-surgical Treatments:

Somatostatin analogues (SSAs):
May 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).

May 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:
May 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).

Is sometimes given after surgery to kill any cancer cells that might remain there. It may also be used for cancer that has spread beyond the primary site, in particular if disease has spread to the bones – here it is used to help control growth of any spread and alleviate bone pain.

Endoscopic procedure:
Treatment given via endoscopy – for example, removal of a stomach or rectal polyp.

Interventional radiology:
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 Trials:
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.

Symptom Control:
Managing symptoms, including pain, 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.

Following surgery/endoscopic resection – for minimum 10 years:

  • G1/2 <1cm: no lymph nodes, no evidence of invasion: there is no data re recommended follow up.
  • G3 <1cm: annual follow up with colonoscopy.
  • G1/2 1-2cm: annual follow up with colonoscopy.
    Biochemistry alongside colonoscopy/scan.

ALL Neuroendocrine Cancers >2cm require ongoing follow up – minimum 10 years (nb metastatic disease has been seen beyond this time):

  • G1/2: annual colonoscopy + CT + biochemistry.
  • G3: 4 – 6 monthly colonoscopy + CT + biochemistry for the first year, then annually.

If liver tumours present – for MRI or contrast CT concurrent with follow up timings.

Advanced disease:

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.