Note: On this page and in a medical context, the terms “small bowel” and “small intestine” are used interchangeably referring to the same anatomical structure.
Small Bowel Neuroendocrine Tumours (NETs) are a complex group of tumours with diverse characteristics and manifestations. While small bowel NETs are less common than other cancers, their impact on patients and their families can be significant, leading to various symptoms and complications.
Classification, grading, and staging are crucial aspects of understanding small bowel tumours, as they influence prognosis and treatment decisions. Accurate diagnosis relies on a combination of clinical, laboratory, and imaging techniques, and the choice of treatment depends on the tumour’s type, grade, stage, and the patient’s overall health.
Treatment options range from surgery to medical therapies and specialised treatments like PRRT, to improve outcomes and the quality of life for individuals affected by small bowel NETs.
NeuroEndocrine Cancer Australia is here for the advocacy and support of all patients affected by NETs and their families. The content covered on this page is purely informational. For specific information related to your diagnosis, contact your healthcare team, or call our NET cancer nurse.
The small intestine (or bowel), comprising the duodenum, jejunum, and ileum, is a vital part of the digestive system responsible for digestion and absorbing nutrients. Small Bowel Neuroendocrine Tumours (NETs), also known as small intestine NETs, are a less common type of cancer that can develop in this region of the gastrointestinal tract.
Small bowel NETs are a subset of neuroendocrine tumours that originate in the neuroendocrine cells of the small intestine. These tumours are characterised by their unique ability to produce hormones and, in some cases, cause overproduction of these hormones.
Small bowel NETs are the most common in the gastrointestinal tract. Understanding their prevalence and incidence is crucial to addressing the challenges associated with diagnosis, treatment, and support for people affected by this disease.
Approximately 5,550 Australians are diagnosed with neuroendocrine tumours each year, with small bowel NETs being a subset of these cases. While this number may seem small compared to other cancer types, it is essential to note that due to their common symptoms, many cases go undiagnosed for some time. This can lead to adverse outcomes for patients affected as their small bowel NETs progress.
In fact, the incidence of small bowel NETs is on the rise. As diagnostic techniques advance and healthcare professionals become more aware of these tumours, more cases are identified.
Small bowel NETs can be challenging to diagnose because they often mimic other common health issues. Understanding the signs and symptoms associated with these tumours is crucial for early detection and timely intervention.
Common symptoms of small bowel NETs include:
It’s important to note that symptoms can vary from person to person, and not all individuals with small bowel NETs will experience all of these symptoms. Symptoms may also depend on the location and size of the tumour. If you exhibit any or a combination of the symptoms above, talk to your GP sooner rather than later.
Pathophysiology is the study of abnormal changes in the body as a result of a disease’s processes. Understanding the pathophysiology of small bowel NETs can provide valuable insights into their formation, growth, spread, and potential treatment options.
Small bowel NETs originate from neuroendocrine cells in the small intestine. These cells are responsible for regulating various functions, including hormone production. While the exact cause of their transformation into cancer cells is not fully understood, genetic mutations and environmental factors can play a role.
Small bowel NETs are generally slow-growing tumours, which can make them difficult to detect in the early stages. They have the potential to metastasise (spread) to nearby lymph nodes and, in advanced cases, to distant organs such as the liver.
The symptoms associated with small bowel NETs are primarily due to the overproduction of hormones by these tumours. The excessive release of hormones disrupts the body’s normal physiological processes and can lead to various symptoms and complications. For example, carcinoid syndrome results from the secretion of hormones such as serotonin and can lead to symptoms like flushing and diarrhoea.
As small bowel NETs grow, they can also interfere with the normal function of the small intestine, affecting digestion and nutrient absorption. This interference can lead to symptoms like abdominal pain, diarrhoea, and weight loss.
The body’s response to the presence of small bowel NETs can sometimes cause additional symptoms or complications. For instance, when the tumours secrete excess hormones, the body may react by producing symptoms like facial flushing or diarrhoea.
Fortunately, a growing understanding of the cellular and molecular abnormalities in small bowel NETs can help identify potential targets for treatment. Therapies may aim to block hormone production, slow tumour growth, or prevent angiogenesis (formation of new blood vessels that feed the tumour).
Small bowel Neuroendocrine Tumours (NETs) encompass a diverse group of tumours with varying characteristics. Understanding how these tumours are classified, graded, and staged is essential for determining prognosis and choosing the most appropriate treatment approach.
Small bowel NETs can be classified into different types based on factors like their cellular origin and functional characteristics. The main types include:
These tumours resemble normal cells and are usually slow-growing. They are further classified into functional and non-functional NETs.
These are aggressive tumours that grow rapidly and are less differentiated than well-differentiated NETs. NECs often require more aggressive treatment approaches due to their rapid growth and tendency to metastasise.
The grading of small bowel NETs is based on the Ki-67 index and mitotic rate, which reflect the tumour’s proliferation (growth) rate. The grading system includes:
Diagnosing small bowel NETs can be complex, as the symptoms can mimic other gastrointestinal disorders. Furthermore, small bowel neuroendocrine tumours may be challenging to detect. Several methods are used in the diagnostic process:
Diagnostic imaging plays a crucial role in diagnosing small intestine NETs. There are 3 main imaging processes that are widely available:
Laboratory tests and biomarkers play an equally crucial role in the diagnosis and management of small bowel NETs. Here are the four main types of laboratory tests to find and diagnose small bowel NETs.
The exact diagnosis process related to your condition will depend on what is agreed upon by your healthcare team. It’s always best to talk to them to understand what the outlook looks like for you.
Fortunately, just as screening and identification become more advanced, so does treatment for small intestine NETs. Several treatment options are available, each with its benefits, risks, and potential outcomes.
Any treatment plan for small bowel NETs is highly individualised and depends on various factors, including:
Surgery: The primary treatment for localised small bowel NETs is surgical resection, which involves removing the tumour and surrounding tissue. The extent of surgery depends on the tumour’s size, location, and whether it has spread to nearby lymph nodes. The goal is to remove as much of the tumour as possible while preserving normal intestinal function.
In some cases, laparoscopic or minimally invasive surgery may be an option, resulting in smaller incisions, less scarring, and a quicker recovery.
These drugs, such as octreotide and lanreotide, can control hormone production in functional NETs, alleviating symptoms like diarrhoea and flushing. It can also help to shrink the tumour.
Targeted therapies, like sunitinib and everolimus, are used for advanced NETs that are not amenable to surgery. They work by inhibiting the growth of NET cells.
In cases of poorly differentiated NECs, chemotherapy may be necessary. Chemotherapy drugs target rapidly dividing cells and aim to slow down or stop the cancer’s progression.
PRRT is a specialised treatment that uses a radioactive substance attached to a somatostatin analogue. It delivers radiation directly to NET cells while sparing healthy tissue. PRRT is primarily used for advanced NETs that express somatostatin receptors.
If the small bowel NET has metastasised to the liver, treatments like transarterial chemoembolisation (TACE), hepatic artery embolisation (HAE) or selective internal radiation therapy (SIRT) may be considered to target liver metastases.
In many cases, a multidisciplinary team, including surgeons, medical oncologists, nuclear medicine physicians, endocrinologists, radiation oncologists, and other specialists, collaborates to provide the most comprehensive and personalised care for patients with small bowel NETs.
Early detection and understanding of these tumours are essential for improving outcomes and providing timely treatment and support to those diagnosed with small bowel NETs.
