Understanding where neuroendocrine tumours (NETs) commonly occur is crucial for early diagnosis, effective treatment, and improving patient outcomes. NETs are a diverse group of malignancies that arise from neuroendocrine cells located throughout the body.
This comprehensive overview from Neuroendocrine Cancer Australia (NECA) explores the primary sites of NET development including the gastrointestinal tract, pancreas, lungs, and reproductive system, as well as addressing the enigmatic category of tumours of unknown primary.
Neuroendocrine Cancer Australia (NECA), is dedicated to assisting individuals with neuroendocrine tumours (NETs). NECA offers a wealth of resources, educational programs, and advocacy efforts aimed at deepening the understanding of NETs, improving patient care, and encouraging research advancements. Patients diagnosed with NETs can engage with NECA’s comprehensive support and information by calling the NET nurse line.
The gastrointestinal tract is the most common location for NETs, reflecting the extensive distribution of neuroendocrine cells within this system.
Gastric NETs often arise from enterochromaffin-like cells in the stomach lining. Elevated gastrin levels can stimulate these tumours due to chronic atrophic gastritis, leading to multiple, small tumours or occasionally larger, isolated masses.
These tumours’ growth can cause various symptoms, including:
Small intestinal NETs, particularly those in the jejunum and ileum, are often slow-growing and small and cause no symptoms until they have spread to other body parts, especially the liver, producing serotonin. This overproduction can lead to carcinoid syndrome, characterised by flushing, diarrhoea, and heart valve problems, especially when liver metastases are present and can bypass the normal metabolic breakdown of serotonin by the liver.
Colorectal NETs, while less common than their gastric and small intestinal counterparts, can significantly impact patient health. Due to their location, they are often detected incidentally during routine screening procedures like colonoscopy.
These tumours may present with symptoms such as:
The symptoms associated with GI-NETs vary widely but often include nonspecific gastrointestinal complaints such as abdominal pain, bloating, and diarrhoea. Specific symptoms such as flushing and diarrhoea are characteristic of carcinoid syndrome, particularly when the disease involves the liver.
P-NETs arise from the islet cells scattered throughout the pancreas. These tumours can be divided into functional and non-functional tumours based on their ability to produce hormones. Let’s look at the classification of P-NETs based on hormone secretion.
Produce insulin excessively, leading to potentially dangerous hypoglycemia. These tumours are often small and benign but can cause significant health issues due to their hormone production.
Secrete gastrin, which stimulates the stomach to produce too much acid, leading to peptic ulcers. This condition is known as Zollinger-Ellison syndrome and can be debilitating without appropriate management.
While rare, these tumours produce glucagon and vasoactive intestinal peptide, respectively, leading to distinct clinical syndromes such as glucagonoma syndrome, characterised by diabetes, weight loss, and a rash, and the watery diarrhoea-hypokalemia-achlorhydria syndrome associated with VIPomas.
Unlike the more common pancreatic adenocarcinomas, which are highly aggressive and often detected at an advanced stage, P-NETs tend to have a better prognosis if identified early. Their management differs significantly, often involving surgical resection even in cases of localised disease.
The diagnosis of P-NETs involves a combination of biochemical tests for hormone levels, advanced imaging techniques to localise the tumours, and histological examination to confirm their nature. Treatment typically involves surgical resection, with somatostatin analogues used to control symptoms in cases of advanced disease, especially in functional tumours.
Pulmonary NETs primarily develop in:
Typical carcinoids are generally slow-growing and less likely to metastasise compared to atypical carcinoids, which are more aggressive and carry a higher risk of spreading both within and beyond the lungs.
The symptoms of pulmonary NETs often mimic those of more common respiratory conditions, leading to delays in accurate diagnosis. Symptoms can include recurrent pneumonia, wheezing, or coughing up blood. Diagnosis often relies on imaging studies such as CT scans and definitive confirmation through histological examination following a biopsy.
There are two common sites where NETs present in males and females:
NETs in the reproductive system can disrupt hormonal balance and potentially cause fertility issues, leading to complex clinical presentations that require specialised treatment and management strategies.
NUPNETs are characterised by metastatic NETs where the primary site of origin remains unidentified, despite thorough investigation. These tumours represent a particular diagnostic challenge because treatment and prognosis are often determined by tumour origin.
The management of neuroendocrine tumours of unknown primary typically focuses on controlling symptoms and managing tumour growth through systemic therapies, as targeted treatment is often only possible by identifying the origin.
Treatment may involve a combination of surgery, radiation therapy, and medical treatments depending on the location and extent of the disease.
NUPNETs frequently metastasise to the liver, bones, and lungs. Treatment strategies often focus on managing the complications arising from these metastases, such as liver dysfunction or bone pain, which can significantly affect the patient’s quality of life.
Neuroendocrine Cancer Australia (NECA) plays a critical role in supporting patients with neuroendocrine tumours (NETs) and their families by providing comprehensive resources and support systems tailored to their unique needs. NECA offers educational materials that help patients and caregivers understand the diagnosis, treatment options, and management of NETs.
NECA also advocates for better patient care and access to new treatments, ensuring that the voices of those affected by NETs are heard in healthcare policy discussions. Through its dedicated nurse helpline, NECA provides direct support and guidance, helping patients navigate their treatment journey and improve their quality of life.
This commitment to support extends to online forums and support groups that facilitate connections among patients and families, creating a community that empowers individuals to face the challenges of living with NETs with confidence and armed with information.
Through continued advancements in diagnostic and treatment methodologies, the outlook for patients with NETs continues to improve, emphasising the importance of specialised care and ongoing patient support.
Further information and support for people diagnosed with NETs is available by calling the NECA NET nurse line.
