Clinical Trials
STELLAR-311
Assess the effectiveness of zanzalintinib compared to everolimus in participants with previously treated, unresectable, locally advanced or metastatic neuroendocrine tumours.
Hormonal Syndromes
Some neuroendocrine cancers (NETs) produce excess hormones. When this happens, it can cause a recognisable pattern of symptoms known as a hormonal syndrome.
Not all NETs are hormone-producing. Tumours that produce excessive hormones, resulting in symptoms, are called “functioning” tumours, while those that don’t are called “non-functioning”. The syndrome a person experiences depends on which hormone is being overproduced and where the tumour started.
Below is a short overview of the main hormonal syndromes seen in neuroendocrine cancer, with links to more detailed information on each tumour type.
Carcinoid syndrome
Carcinoid syndrome occurs when certain NETs, most often midgut NETs that have spread to the liver, release excess serotonin and other substances into the bloodstream.
Common symptoms include flushing, diarrhoea, abdominal cramping, and wheezing.
Carcinoid heart disease
Long-term exposure to high serotonin levels can damage the heart valves over time, a condition known as carcinoid heart disease. It usually develops in people who have not been monitored or had poor controlled carcinoid syndrome for an extended period.
Symptoms can include shortness of breath, fatigue, and swelling in the legs or abdomen. Regular heart monitoring (echocardiogram) is recommended for people with carcinoid syndrome.
Zollinger-Ellison syndrome (Gastrinoma)
Gastrinomas are pancreatic or duodenal NETs that produce excess gastrin, a hormone that stimulates stomach acid. When gastrin levels become too high, the resulting excess acid can cause severe and recurring peptic ulcers, abdominal pain, and diarrhoea. This group of symptoms is known as Zollinger–Ellison syndrome.
Insulinoma syndrome
Insulinomas are pancreatic NETs that produce excess insulin, causing low blood glucose levels (hypoglycaemia). Symptoms can include sweating, shakiness, confusion, and fainting, often relieved by eating.
VIPoma (Verner-Morrison syndrome)
VIPomas are rare pancreatic NETs that release excess vasoactive intestinal peptide (VIP). This leads to a distinctive pattern of severe watery diarrhoea, low potassium levels, and reduced stomach acid, sometimes called Verner-Morrison syndrome or WDHA (Water Diarrhoea, Hypokalaemia and Achlorhydria) syndrome.
Glucagonoma syndrome
Glucagonomas are rare pancreatic NETs that produce excess glucagon. This can cause a characteristic skin rash, weight loss, high blood sugar, and an increased risk of blood clots.
Somatostatinoma syndrome
Somatostatinomas are rare pancreatic NETs that produce excess somatostatin. This can cause diabetes, gallstones, and digestive symptoms such as diarrhoea and weight loss, although many somatostatinomas are found incidentally without obvious symptoms.
Catecholamine excess (phaeochromocytoma and paraganglioma)
Phaeochromocytomas and paragangliomas (PPGLs) are tumours that may produce excess catecholamines, including adrenaline and noradrenaline. This can cause episodes of high blood pressure, severe headaches, sweating, and palpitations.
These tumours are more commonly associated with inherited genetic syndromes than many other NETs, including von Hippel-Lindau (VHL) syndrome, Multiple Endocrine Neoplasia type 2 (MEN2), and Neurofibromatosis type 1 (NF1) and SDH complex.
Genetic syndromes linked to hormone-producing NETs
Some hormonal syndromes occur as part of an inherited condition, where a person has a higher chance of developing one or more NETs over their lifetime. These include:
- Multiple Endocrine Neoplasia type 1 (MEN1) – associated with pancreatic NETs, parathyroid tumours, and pituitary tumours
- Multiple Endocrine Neoplasia type 2 (MEN2) – associated with medullary thyroid carcinoma and phaeochromocytoma
- Von Hippel-Lindau (VHL) syndrome – associated with pancreatic NETs and phaeochromocytoma/paraganglioma
- Neurofibromatosis type 1 (NF1) – associated with phaeochromocytoma and duodenal NETs
- SDH complex – SDHA, SDHB, SDHC, SDHD, SDHAF2 associated with paragangliomas and phaeochromocytomas
If a hormonal syndrome is linked to an inherited condition, genetic counselling and family screening may be recommended.
FAQs about hormonal syndromes
A hormonal syndrome is a pattern of symptoms caused by a neuroendocrine cancer producing excess hormones.
No. Many neuroendocrine cancers (NETs) are "non-functioning" and do not produce excess hormones. Hormonal syndromes only occur with "functioning" tumours.
Yes. Treatment may include medication to control symptoms, somatostatin analogues, surgery to remove the tumour, or other targeted therapies depending on the tumour type and location.
No. Carcinoid syndrome is one specific type of hormonal syndrome. Others, such as Zollinger-Ellison syndrome or VIPoma, are caused by different hormones and have different symptoms.
Some can. Certain hormone-producing NETs are linked to inherited genetic syndromes, such as MEN1, MEN2, VHL, and NF1. Genetic counselling can help clarify the risk to you and your family.
Support available through NeuroEndocrine Cancer Australia
If you or someone you care for has been diagnosed with a hormone-producing neuroendocrine tumour, NeuroEndocrine Cancer Australia provides:
- Access to the NET Nurse service
- Specialist NET dietitian
- Specialist NET counsellor
- Patient and carer information
- Support for navigating rare NET care
- Education about neuroendocrine cancer
- Guidance on questions to ask your healthcare team
- Connection to relevant support resources
