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Neuroendocrine tumors

Neuroendocrine tumors (NETs) arise from specialized hormone-producing neuroendocrine cells found throughout the body. Once considered exceptionally rare, their incidence has more than sextupled over the past four decades — driven largely by advances in imaging, pathology, and clinical awareness. NETs range from slow-growing tumors with favorable long-term outcomes to aggressive malignancies that spread rapidly. Understanding this spectrum is essential to timely diagnosis and appropriate management

Prevalence

2.5–6.7 / 100,000

8,275–22,177

US Estimated

12,825–34,371

EUROPE ESTIMATED

Age of Onset

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Typically 40–65 years; median age at diagnosis ~63 years

ICD-10

C7A – Malignant carcinoid

D3A — Benign carcinoid

C25.4 — Malignant islet cell/PNET

Inheritance Pattern

Autosomal dominant

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Most neuroendocrine tumors are sporadic, though some are associated with autosomal dominant hereditary syndromes including MEN1 and MEN2

Autosomal recessive

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Mitochondrial/Multigenic

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X-linked dominant

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Autosomal dominant

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5 Facts you should know

FACT

1

NETs are far more common than once believed
Incidence has increased more than sixfold over the past 40 years — from 1.09 to 6.98 per 100,000 — making NETs one of the fastest-growing cancer diagnoses in the U.S. This rise reflects improved imaging, better pathological recognition, and more widespread endoscopic surveillance, not a true increase in disease burden alone

FACT

2

Most NETs are non-functioning — and silent
Approximately 60–70% of NETs do not produce a clinically recognizable hormonal syndrome. These tumors are frequently discovered incidentally on imaging performed for unrelated reasons, often when already locally advanced or metastatic. The absence of symptoms does not indicate biological indolence

FACT

3

Ki-67 index is the cornerstone of diagnosis and treatment planning
The WHO 2022 grading system classifies NETs based on Ki-67 proliferation index: G1 (<3%), G2 (3–20%), G3 (>20%), with poorly differentiated NECs forming a separate category. Grade determines prognosis, imaging approach, and systemic therapy selection — making Ki-67 the single most important pathological result in NET management

FACT

4

Somatostatin receptor status is both a diagnostic and therapeutic key
Most well-differentiated NETs overexpress somatostatin receptors (especially SSTR2), enabling highly sensitive 68Ga-DOTATATE PET-CT imaging and eligibility for peptide receptor radionuclide therapy (PRRT) with Lutetium-177 DOTATATE (Lutathera). Receptor status is therefore a critical biomarker that directly opens — or closes — a treatment pathway

 

FACT

5

Up to 10% of NETs occur in the context of a hereditary syndrome
NETs associated with MEN1, MEN2, VHL syndrome, NF1, or Tuberous Sclerosis Complex often present at a younger age, are multifocal, and require germline testing and coordinated surveillance across multiple organ systems. Genetic counseling should be considered in all patients with young onset, family history, or multifocal disease

Neuroendocrine tumors are also known as...

Neuroendocrine tumors are also known as:

  • Carcinoid tumors

  • Islet cell tumors (pancreatic NETs)

  • GEP-NETs (gastroenteropancreatic)

  • APUDomas, neuroendocrine neoplasms (NENs)

What’s your Rare IQ?

In the grading of well-differentiated neuroendocrine tumors, which biomarker is most commonly used to classify tumors as G1, G2, or G3?

Common signs & symptoms

Carcinoid syndrome

Episodic skin flushing, secretory diarrhea, wheezing/bronchoconstriction, telangiectasias — caused by serotonin and vasoactive peptides; typically in metastatic midgut NETs

Insulinoma

Whipple's triad — hypoglycemia symptoms with fasting, blood glucose <55 mg/dL, relief with glucose; most common functional pancreatic NET

Gastrinoma (Zollinger-Ellison Syndrome)

Severe/recurrent peptic ulcers, GERD, diarrhea, elevated fasting serum gastrin

VIPoma

Profuse watery diarrhea, hypokalemia, achlorhydria (WDHA/Verner-Morrison syndrome)

Glucagonoma

Necrolytic migratory erythema (pathognomonic rash), new-onset diabetes, weight loss, anemia

Current treatments

Treatment depends on disease severity and organ involvement.

Surgery

Resection remains the only potentially curative approach for localized or regional disease. Liver-directed therapies (hepatic artery embolization, ablation, surgical cytoreduction) are considered for liver-dominant metastatic disease in selected patients

Somatostatin Analogs (SSAs)

Octreotide LAR (Sandostatin LAR, Novartis) and lanreotide (Somatuline Depot, Ipsen) are FDA-approved for symptomatic control of carcinoid syndrome and have demonstrated antiproliferative activity. The PROMID and CLARINET trials established benefit in midgut and non-functional NETs respectively

Peptide Receptor Radionuclide Therapy (PRRT)

Lutetium-177 DOTATATE (Lutathera, Advanced Accelerator Applications/Novartis) was FDA-approved in 2018 for somatostatin receptor-positive GEP-NETs progressing on SSAs. The NETTER-1 trial demonstrated a 79% reduction in risk of progression or death vs. high-dose octreotide (HR 0.18)

mTOR Inhibition

Everolimus (Afinitor, Novartis) is FDA-approved for advanced progressive non-functional GI and lung NETs (RADIANT-4 trial) and for pancreatic NETs (RADIANT-3 trial)

Tyrosine Kinase Inhibition

Sunitinib (Sutent, Pfizer) is FDA-approved for progressive, well-differentiated, malignant pancreatic NETs based on significant PFS improvement in its pivotal Phase III trial

Antisecretory Therapy

Telotristat ethyl (Xermelo, Lexicon) is a tryptophan hydroxylase inhibitor FDA-approved for carcinoid syndrome diarrhea inadequately controlled on SSAs (TELESTAR trial)

Chemotherapy

Temozolomide ± capecitabine (TEMCAP) is widely used for higher-grade NETs, PRRT-refractory disease, and pancreatic NETs. Streptozocin-based regimens retain historical use for PNETs. Platinum/etoposide ± immunotherapy is used for poorly differentiated NECs, including SCLC-type

Clinical trials

TitleDescriptionPhasesStatusInterventionsMore Information
DAREON®-NEC-1: A Study in People With Advanced Extrapulmonary Neuroendocrine Cancer to Compare Obrixtamig Plus Carboplatin and Etoposide Treatment With Standard ChemotherapyThis study is open to adults with advanced extrapulmonary neuroendocrine cancer. The purpose of this study is to find out if a study medicine called obrixtamig plus standard chemotherapy (carboplatin and etoposide) improves survival when compared to standard chemotherapy (carboplatin and etoposide)...Phase 3Not yet recruitingDrug: Obrixtamig
Drug: Carboplatin
Drug: Etoposide
Device: Ventana DLL3 RxDx assay
More Info
DAREON™-5: A Study to Test Whether Different Doses of BI 764532 Help People With Small Cell Lung Cancer or Other Neuroendocrine CancersThis study is open to adults with small cell lung cancer and other neuroendocrine tumours. The study is in people with advanced cancer for whom previous treatment was not successful or no standard treatment exists.

The purpose of this study is to find a suitable dose of BI 764532 (also called obrix...
Phase 2RecruitingDrug: BI 764532, dose 1
Drug: BI 764532, dose 2
More Info
DAREON™-7: A Study to Test How Well Different Doses of BI 764532 in Addition to Chemotherapy Are Tolerated by People With Advanced Neuroendocrine CancersThis study is open to adults aged 18 and older or above legal age who have a specific type of advanced neuroendocrine cancer (NEC). Their tumours must be positive for a marker called DLL3.

The purpose of this study is to test a medicine called BI 764532 in addition to chemotherapy. The study has Pa...
Phase 1RecruitingDrug: BI 764532
Drug: Carboplatin
Drug: Etoposide
Drug: Cisplatin
More Info
A Study to Test Different Doses of Obrixtamig in Patients With Small Cell Lung Cancer and Other Neuroendocrine Tumours That Are Positive for DLL3This study is open to adults with small cell lung cancer and other neuroendocrine cancers that are positive for the tumour marker delta-like 3 (DLL3). The study is in people with advanced cancer for whom previous treatment was not successful or no standard treatment exists.

The purpose of this stud...
Phase 1RecruitingDrug: Obrixtamig - parenteral 1
Drug: Obrixtamig - parenteral 2
More Info
A Study to Test How Well Different Doses of Obrixtamig (BI 764532) in Combination With Ezabenlimab Are Tolerated by People With Small Cell Lung Cancer and Other Neuroendocrine Tumours That Are Positive for DLL3This study is open to adults with small cell lung cancer and other neuroendocrine tumours that are positive for the tumour marker Delta-like 3 (DLL3). The study is in people with advanced cancer for whom previous treatment was not successful or no standard treatment exists.

The purpose of this stud...
Phase 1ActiveDrug: Obrixtamig
Drug: Ezabenlimab
More Info
A Study to Test How BI 764532 is Taken up by Tumours in People With Small-cell Lung Cancer or Neuroendocrine CancerThis study is open to adults with small cell lung cancer and other neuroendocrine cancers. The study is in people with advanced cancer for whom previous treatment was not successful or no standard treatment exists. The purpose of this study is to find out how a medicine called BI 764532 gets distrib...Phase 1RecruitingDrug: BI 764532
Drug: [89Zr]Zr-BI 764532
More Info
Efficacy and Safety of 177Lu-edotreotide PRRT in GEP-NET PatientsThe purpose of the study is to evaluate efficacy and safety of Peptide Receptor Radionuclide Therapy (PRRT) with 177Lu-Edotreotide compared to targeted molecular therapy with Everolimus in patients with inoperable, progressive, somatostatin receptor-positive (SSTR+), neuroendocrine tumours of gastro...Phase 3ActiveDrug: 177Lu-edotreotide PRRT
Drug: Everolimus
Other: Amino-Acid Solution
More Info
Study of Cabozantinib With Lu-177 in Patients With Somatostatin Receptor 2 Positive Neuroendocrine TumorsThe phase I objective of this study is to establish the maximal tolerated dose (MTD) of cabozantinib in 20 mg, 40 mg and 60 mg dose escalation cohorts in combination with Lu-177 dotatate at a standard dose of 7.4 GBq in four (4) 8-week cycles followed by continuation cabozantinib.Phase 1ActiveDrug: Cabozantinib
Drug: Lu-177
More Info
A First-in-Human Phase I Trial With Antibody Drug Conjugate ADCT-701 in Neuroendocrine Tumors, Carcinomas and Malignant Peripheral Nerve Sheath TumorsBackground:

Neuroendocrine neoplasms (NENs) are rare cancers in the gastrointestinal tract, pancreas, lungs, adrenal glands, and other areas of the body. Many of these cancers have a high risk of relapse and a low chance of survival. Better treatments are needed.

Objective:

To test a new drug, AD...
Phase 1RecruitingDrug: ADCT-701More Info
SVV-001 With Nivolumab and Ipilimumab in Patients With Poorly Differentiated Neuroendocrine Carcinomas (NEC) or Well-Differentiated High-Grade Neuroendocrine Tumors (NET)The purpose of this study is to determine:

1. The highest dose of the trial intervention that targets neuroendocrine tumors and is tolerated by patients.
2. The highest frequency of dosing of the trial intervention that targets neuroendocrine tumors and is tolerated by patients.
3. The highest dose...
Phase 1RecruitingBiological: Seneca Valley Virus-001 (SVV-001)
Drug: Nivolumab
Drug: Ipilimumab
More Info