Understanding the Disease

What is an intestinal neuroendocrine tumour?

Neuroendocrine tumours (NETs) arise from the body's hormone-producing neuroendocrine cells, which are scattered throughout the gut wall. When they occur in the intestine — most commonly the small bowel (ileum), but also the appendix, colon and rectum — they are called intestinal or GI NETs. Older texts call small-bowel NETs "carcinoid tumours."

They are usually slow-growing. Many are found incidentally during surgery or a scan done for another reason. But because they can spread to lymph nodes and the liver — and because some secrete hormones — they need careful, NET-specific assessment rather than being treated like ordinary bowel cancer.

Some intestinal NETs are functional, releasing hormones (such as serotonin) that cause carcinoid syndrome — flushing, diarrhoea, and over years, heart-valve changes (carcinoid heart disease). Most, however, are non-functional and present with vague abdominal pain, bowel obstruction, or are found during imaging.

A characteristic feature of small-bowel NETs is a fibrotic (desmoplastic) reaction in the mesentery that can tether the bowel and encase blood vessels — an important surgical consideration we plan for carefully.

Why NETs need a dedicated approach

NETs are staged, graded, imaged and treated differently from adenocarcinomas. The same tumour size can mean very different things depending on grade. Specialist NET imaging (DOTATATE PET) and NET-specific markers guide therapy, and even with spread to the liver, patients often live many years with the right combination of surgery, somatostatin analogues and PRRT. A NET diagnosis is not the same conversation as a typical cancer diagnosis.

Grading

WHO grading — the single most important number

Grade describes how fast the tumour cells divide, measured by the Ki-67 index and mitotic count. It drives almost every treatment decision.

Grade 1 (Low)

Ki-67 under 3%. Slow-growing, well-differentiated. The commonest intestinal NET. Often managed with surgery and/or somatostatin analogues, with excellent long-term outlook.

Grade 2 (Intermediate)

Ki-67 3–20%. Still well-differentiated but more active. Needs closer monitoring and a lower threshold for systemic therapy alongside surgery.

Grade 3 NET

Ki-67 over 20% but still well-differentiated. Behaves more aggressively; treatment is individualised and may include chemotherapy.

NEC (Poorly differentiated)

Neuroendocrine carcinoma — a distinct, aggressive disease treated more like high-grade carcinoma, primarily with chemotherapy. Different from a Grade 3 NET despite a similar Ki-67.

How grade is measured

On the biopsy or resected specimen, the pathologist counts mitoses and stains for Ki-67. Accurate grading needs adequate tissue — another reason for specialist pathology review.

Why it matters to you

Grade, more than size, predicts behaviour and shapes whether you need surgery alone, surgery plus medication, PRRT, or chemotherapy.

Staging

From biopsy to a complete picture

Staging (TNM) maps how far the NET has spread — local bowel wall, mesenteric lymph nodes, and distant sites, most often the liver. Every case is reviewed at a multidisciplinary tumour board before treatment.

Stage 1–2

Localised to the bowel wall

Tumour confined to the intestine. Surgery is usually curative. Many appendiceal and small rectal NETs fall here and need only complete local removal.

Stage 3

Mesenteric lymph node spread

Common in small-bowel NETs, often with the characteristic mesenteric fibrosis. Surgery aims to clear the primary and the nodal mass while protecting the bowel's blood supply.

Stage 4

Distant spread — usually liver

Even at this stage, outcomes can be good over many years. A combined plan — somatostatin analogues, PRRT, liver-directed therapy and selective surgery — controls the disease.

MDT

Tumour board decision

Surgeons, medical oncologists, nuclear medicine, radiology and pathology agree the sequence: who needs surgery first, who needs medication first, and who needs both.

Investigations · Imaging · Tumour Markers

How intestinal NETs are worked up

NETs need NET-specific tests. Standard cancer imaging and markers can miss them — which is why specialist functional imaging and the right blood tests are essential.

Imaging

Ga-68 DOTATATE PET-CT — the key scan

NET cells carry somatostatin receptors that this scan lights up. It finds the primary, nodal and liver disease that ordinary scans miss, and confirms the tumour is "DOTATATE-avid" — which also predicts whether PRRT will work.

Imaging

Triple-phase CT / MRI abdomen

Maps the primary tumour, mesenteric mass and liver metastases in anatomical detail for surgical planning. MRI liver is especially sensitive for small NET liver deposits.

Endoscopy

Colonoscopy & capsule / device endoscopy

For rectal and colonic NETs, and to locate small-bowel primaries that imaging cannot pinpoint. Endoscopic ultrasound assesses depth for small rectal NETs.

Marker

Chromogranin A (CgA)

The main blood marker for NETs — useful for monitoring disease and response over time. Levels can be affected by acid-lowering medication, which we account for.

Marker

24-hour urinary 5-HIAA

Measures serotonin breakdown products — raised in functional small-bowel NETs and central to diagnosing and tracking carcinoid syndrome. Needs a specific pre-test diet.

Assessment

Echocardiography & specialist bloods

If carcinoid syndrome is present, an echo screens for carcinoid heart disease. Targeted hormone tests are added when a specific functional syndrome is suspected.

Treatment

Non-surgical and surgical — a combined plan

Most intestinal NETs are managed with a sequence of treatments rather than one. The grade, stage, whether the tumour is functional, and the DOTATATE scan together decide what comes first.

ADD PHOTO

NET surgery & DOTATATE imaging

Add a theatre / DOTATATE PET / specimen image here (16:9 landscape)

Non-Surgical Treatment

Controlling the disease medically

First line

Somatostatin analogues (octreotide / lanreotide)

Monthly injections that both control hormone symptoms and slow tumour growth in well-differentiated NETs — a cornerstone of long-term management.

Targeted

PRRT — Lu-177 DOTATATE

Peptide receptor radionuclide therapy delivers radiation directly to DOTATATE-avid tumour cells. For progressive small-bowel NETs it improves disease control, as shown in the NETTER-1 trial.

Systemic

Targeted agents & chemotherapy

Everolimus and, in selected cases, chemotherapy are reserved for higher-grade or progressive disease. Poorly differentiated NEC is treated primarily with chemotherapy.

Liver-directed

Embolisation & ablation

For liver metastases not suited to surgery, TACE/TAE or ablation reduce tumour bulk and hormone output, often alongside somatostatin analogues.

Symptom

Carcinoid syndrome control

Somatostatin analogues, plus telotristat where needed, control flushing and diarrhoea. Crucially, we cover patients during surgery to prevent carcinoid crisis.

Surgical Treatment

When surgery is required

Surgery is the only curative treatment for localised intestinal NETs, and remains valuable even with limited spread. It is indicated when:

Curative

Localised small-bowel NET

Segmental small-bowel resection with mesenteric lymphadenectomy — clearing the nodal disease while preserving bowel length and the mesenteric vessels. The whole small bowel is inspected, as these tumours can be multiple.

Indicated

Obstruction or mesenteric mass

Even with metastatic disease, removing the primary and a fibrotic mesenteric mass prevents bowel obstruction and ischaemia, and improves quality of life.

Appendiceal

Appendiceal & rectal NETs

Small low-grade appendiceal or rectal NETs may be cured by appendicectomy or local excision; larger or higher-grade ones need a formal cancer resection (right hemicolectomy or rectal surgery).

Selective

Liver cytoreduction (debulking)

Removing or ablating the bulk of liver metastases can dramatically reduce hormone symptoms and prolong control — a NET-specific principle where debulking helps even when complete clearance isn't possible.

Safety

Perioperative octreotide cover

For functional tumours, octreotide is given around surgery to prevent carcinoid crisis — a key safety step that needs an experienced NET team and anaesthetist.

Minimally invasive

Robotic & laparoscopic resection

Where suitable, minimally invasive surgery offers faster recovery with the same oncological clearance — chosen case by case.

Mesenteric lymphadenectomy Bowel-length preservation Cholecystectomy (with SSA) Liver debulking Octreotide cover ERAS recovery

Follow-Up

NETs are a long-term relationship

Because well-differentiated NETs grow slowly and can recur late, follow-up is planned over years, not months — tailored to grade and stage.

Schedule

Regular review by grade & stage

Low-grade resected NETs are followed less intensively but for longer; higher-grade or metastatic disease is reviewed more frequently. Surveillance often continues for ten years or more.

Tests

Markers & imaging at each visit

Chromogranin A (and 5-HIAA if functional), with CT or MRI. DOTATATE PET is repeated when recurrence is suspected or before considering PRRT.

Monitoring

Carcinoid heart & nutrition

Periodic echocardiography in functional disease, plus vitamin B12 and bile-salt monitoring after small-bowel resection, and gallstone surveillance on long-term somatostatin analogues.

Support

Symptom & quality-of-life care

Diet advice for diarrhoea, injection scheduling, and prompt access for new symptoms — managed as an ongoing partnership rather than discharge after surgery.

Patient Questions

Intestinal NETs — answered plainly

Yes, but a special kind. Most intestinal NETs are slow-growing and behave very differently from common bowel cancer. Many people live for many years — often a normal lifespan with low-grade disease — which is why they are managed by a dedicated NET team rather than treated like an ordinary cancer.

Grade (G1–G3, by Ki-67) describes how fast the cells divide; stage describes how far the tumour has spread. For NETs, grade is often more important than size in predicting behaviour and choosing treatment.

NET cells carry somatostatin receptors that a Ga-68 DOTATATE PET-CT lights up. It finds disease ordinary scans miss and confirms the tumour is "DOTATATE-avid" — which tells us whether targeted PRRT treatment is likely to work for you.

When a small-bowel NET (usually after it has spread to the liver) releases hormones like serotonin, it can cause flushing, diarrhoea and, over time, heart-valve changes. It is controlled with somatostatin analogues, and we give extra cover around surgery to prevent a "carcinoid crisis."

Not always. Localised NETs are usually cured by surgery, and surgery remains useful even with some spread — to prevent obstruction or to debulk liver disease. But low-volume or widespread disease may be managed first with somatostatin analogues and PRRT. The plan is decided at the tumour board for your specific case.

Yes — and often with good results over many years. Options include surgical debulking, ablation or embolisation of liver deposits, somatostatin analogues and PRRT, used in combination. Liver spread in NETs is not the same prognosis as in ordinary cancer.

This page is general information, not personal medical advice. Neuroendocrine tumour treatment is always individualised at a multidisciplinary tumour board. Please bring all scans, DOTATATE PET reports and biopsy results to your consultation.

Silver Leaf Clinic · Hadapsar, Pune

Book your NET consultation

Dr. Gore sees neuroendocrine and GI cancer patients at Silver Leaf Clinic, Hadapsar. Please bring all CT/MRI scans, DOTATATE PET reports, biopsy results and blood tests (including chromogranin A and 5-HIAA if done) to the first consultation — ideally on CD or shared via WhatsApp in advance.

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