Please note: NECA will be closed from Friday 22nd December, reopening on Monday 8th January
Gastrointestinal (GI) cancer, also known as gastrointestinal tract cancer, is a term encompassing a group of cancers that affect the digestive system. Among these gastrointestinal neuroendocrine tumours are a subset that has gained attention due to their unique characteristics and clinical implications.
On this page, we’ll delve into the causes, symptoms and sites of GI neuroendocrine cancers.
The symptoms of Gastrointestinal Neuroendocrine Tumours (GI NETs) can vary depending on factors such as the tumour’s type, size, and location within the gastrointestinal tract. While these tumours exhibit unique characteristics, there are several common symptoms that individuals may experience:
It’s important to note that the symptoms of GI NETs can overlap with those of other gastrointestinal conditions. Therefore, a thorough evaluation by a healthcare professional is crucial for an accurate diagnosis. Early detection and intervention can significantly improve the prognosis for individuals with GI NETs.
If you or someone you know is experiencing any of these symptoms, it is advisable to seek medical attention promptly to assess and address the underlying cause.
Understanding the causes of Gastrointestinal Neuroendocrine Tumours (GI NETs) involves considering a complex interplay of genetic, environmental, and lifestyle factors. While no single factor is solely responsible, several key factors have been identified that can potentially increase the risk of GI NETs.
Similar to many cancers, genetic predisposition plays a significant role in the development of GI NETs. Individuals with a family history of GI NETs or certain genetic syndromes, such as Multiple Endocrine Neoplasia Type 1 (MEN1) or Von Hippel-Lindau (VHL) syndrome, are at a higher risk.
Although NETs can occur at any age, there are some age groups that specific NETs can
occur in, such as appendiceal NETs in a younger age group.
Dietary and lifestyle choices can also influence the development of GI NETs. While the evidence is not as extensive as for other cancers, diets rich in certain components, such as processed foods or high levels of dietary fat, may contribute to an increased risk. However, more research is needed to establish these links definitively.
Chronic inflammation within the gastrointestinal tract, often associated with conditions like chronic gastritis or inflammatory bowel diseases (IBD), may create an environment conducive to the development of GI NETs. Individuals with these underlying medical conditions may be at a higher risk.
GI NETs can also come from a range of other conditions, including:
GI NETs are neuroendocrine tumours, meaning they originate from neuroendocrine cells that produce hormones. Hormonal imbalances, whether due to certain medical conditions, may contribute to the development of GI NETs.
Understanding the causes of gastrointestinal neuroendocrine tumours is an ongoing area of research, and it’s important to note that not all cases can be attributed to specific risk factors. As with many cancers, early detection, regular screenings for those at higher risk, and a healthy lifestyle are essential in reducing the risk and managing GI NETs effectively.
Gastroenteropancreatic Neuroendocrine Tumours (GEP-NETs) encompass a group of diverse tumours that affect the gastrointestinal tract and pancreas. Gastric Neuroendocrine Tumours, specifically those originating in the stomach, warrant closer examination.
There are four distinct types of gastric NETs, each possessing unique characteristics and implications for diagnosis and treatment.
The most prevalent subtype of GEP-NETs is Type I Gastric NETs, which often emerge alongside atrophic gastritis. In this scenario, an excessive production of gastrin occurs, a condition known as hypergastrinemia. Characterised by the presence of small polyps measuring less than 1–2 cm, these tumours are sometimes discovered during gastroscopy.
Although not always cancerous, these polyps may reoccur, necessitating careful monitoring. While not a certain cause, the prolonged use of proton pump inhibitors (anti-acid medications) for gastric reflux or dyspepsia might elevate the risk of developing Type I Gastric NETs.
Type II Gastric NETs, on the other hand, are rarer and can be linked to a hereditary condition known as multiple endocrine neoplasia type 1 (MEN 1). This subtype involves excessive secretion of the hormone gastrin by a tumour (gastrinoma), causing overproduction of stomach acid and leading to Zollinger–Ellison syndrome. These stomach tumours are typically small and are often managed through monitoring via endoscopic ultrasound.
Type III Gastric NETs, although infrequent, present distinct challenges. Often larger, measuring over 2 cm, these tumours have the potential to metastasize to other parts of the body. As such, surgical removal becomes imperative to address their aggressive nature.
Type IV Gastric NETs stand as the rarest and most complex form. These tumours are often sizable and may have already spread (metastasized) by the time of diagnosis. Managing Type IV Gastric NETs presents substantial difficulties due to their advanced stage.
There are other types of gastroenteropancreatic that affect other areas of the gastrointestinal system that also require examination.
Duodenal NETs, situated in the duodenum, produce an array of hormones and peptides including serotonin, calcitonin, and gastrin somatostatin. Patients with duodenal NETs might experience symptoms such as ‘carcinoid syndrome,’ abdominal pain, or fatigue stemming from anaemia.
NETs originating in the jejunum and ileum often adopt a slow-growing nature and lack prominent symptoms in their early stages. This delayed manifestation complicates their timely diagnosis, with larger tumours and potential metastasis being common by the time of diagnosis. Symptoms might include abdominal pain, bowel obstructions, or even carcinoid syndrome.
Large bowel NETs, particularly in the colon, are infrequent occurrences. These tumours can be substantial, displaying aggressive tendencies and the capacity to spread, causing bowel obstructions and bleeding. In cases where the NET has extended to the liver, wheezing, facial flushing, and watery diarrhoea might emerge as symptoms.
Appendiceal Neuroendocrine Tumours (NETs) often come to light during surgery intended for appendicitis. If these tumours measure less than 1 cm in size, additional surgical interventions are frequently unnecessary, as the tumours may not warrant further immediate attention.
Goblet cell carcinomas, a distinctive subtype, showcase “goblet” shaped cells when examined under a microscope. These tumours might be identified when seeking treatment for acute appendicitis, abdominal pain, or the detection of an abdominal mass.
Notably, women with this particular type of NETs could also exhibit metastases in the ovary, adding an additional layer of complexity to the diagnosis.
Rectal NETs often come to light serendipitously, sometimes during procedures like endoscopy. While patients might present symptoms such as rectal bleeding or changes in bowel habits, many cases manifest without noticeable symptoms. The challenge lies in cases where the tumour remains asymptomatic, potentially leading to metastasis before it is detected.
Pancreatic NETs are split into two distinct groups: functioning and nonfunctioning. Functioning pNETs evoke symptoms by excessively producing hormones, leading to a range of distinct effects:
Non-functioning pNETs may generate hormones and peptides that do not produce overt effects. Consequently, patients often seek medical attention when symptoms like abdominal or back pain arise due to the tumour’s growth, often leading to a delayed diagnosis.
The diagnosis of Gastrointestinal Neuroendocrine Tumours (GI NETs) involves a comprehensive approach that includes imaging studies such as CT scans, MRIs, and endoscopies, as well as blood tests to measure specific markers. The choice of treatment options is influenced by various factors, including the tumour’s size, location, and stage.
Surgery to remove the tumour is a common and primary approach for GI NETs where possible. Surgeons strive to remove the tumour while preserving healthy tissue, whenever feasible. The specific surgical technique employed depends on the tumour’s location and extent.
In cases of advanced GI NETs or when surgery alone is not sufficient, targeted therapies may be considered, for example, PRRT or oral therapies. These therapies aim to interfere with the mechanisms that drive tumour growth. Targeted treatments can be tailored to the tumour’s unique characteristics.
Depending on the individual characteristics of the GI NET and its stage, other medical interventions, such as somatostatin analogs and chemotherapy, can be explored. These therapies can help control hormone secretion and manage symptoms associated with certain types of GI NETs.
Radiation therapy may be used in select cases to target and shrink GI NETs. This approach is often employed when surgical removal is challenging due to the tumour’s location or if there is residual disease following surgery.
It’s important to note that the treatment plan for GI NETs is highly personalised, and decisions are made in consultation with a medical oncologist or a multidisciplinary team of specialists. Treatment choices take into account factors such as the tumour’s biology, grade, stage and the patient’s overall health.
Gastrointestinal Neuroendocrine Tumours (GI NETs) present a unique challenge in the realm of gastrointestinal cancer. Early detection and a tailored treatment approach are crucial for managing these tumours effectively. Medical advancements continue to shape the landscape of GI NETs treatment, offering hope for improved outcomes and quality of life for those affected.
