Introduction
Neuroendocrine cells are characterized by their innate ability to act as both nerve cells and hormone-producing cells. Abnormal overgrowth of these cells leads to the occurrence of neuroendocrine neoplasms (NENs). These tumors are highly rare in incidence and may present themselves anywhere in the body. The rectum, pancreas, small intestine, appendix, and lungs are the most often affected organs. The rate of growth for every tumor varies greatly. A select type of neoplasm produces hormones in excess amounts, known as functional neuroendocrine tumors. Whereas, others are non-responsive and produce almost nil symptoms. Such tumors are referred to as non-functional endocrine tumors. There are various methods used to diagnose tumors, which this article will go into detail about. Every tumor portrays itself differently based on how aggressive it is, and what stage it belongs to. This article's primary focus will be on the role that radiologists play in predicting the prognosis of neuroendocrine tumors.
What Causes Neuroendocrine Tumors?
A tumor arises from an uncontrolled cell division. Neuroendocrine tumors arise when neuroendocrine cells multiply in number, exceeding the normal physiological limit. So far, the precise cause of the cells' aberrant response has not been found. However, theories propose that mutations in the DNA of these cells are responsible for them to multiply in such an abnormal manner. Every tumor is unique. While some tumors develop incredibly slowly, others metastasize, or spread over the surrounding areas, much more quickly. Those with genetic abnormalities that raise the risk of cancer are more likely to develop neuroendocrine tumors. These include tuberous sclerosis, Von - Hippel Lindau disease, neurofibromatosis, and Multiple Endocrine Neoplasia (MEN) - type 1 and type 2.
How Are Neuroendocrine Tumors Diagnosed?
The diagnostic tests to confirm the presence of the neoplasm are determined based on the suspected location of the tumor in the body. General tests include:
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Physical Examination: Here, the doctor assesses the patient for any abnormal signs or symptoms and checks for any noticeable lumps or swollen lymph nodes present in the body.
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Hormone Test: The blood or urine sample undergoes thorough laboratory assessment to confirm the oversecretion of any hormone in the body. Functional neoplasms tend to produce excess hormones in many patients.
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Imaging Tests: Radiology aids in identifying and staging of the tumor further by showing the clear picture as is. Several modalities like ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) are adopted to obtain images of the tumor.
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Biopsy: The tumor cells are collected as a sample that undergoes further testing to confirm the cancer. This procedure may end up being a surgical one, based on the location of the tumor.
How Are Neuroendocrine Tumors Presented Radiographically?
The most common site for the incidence of neuroendocrine tumors is the gastrointestinal tract (GIT). These tumors are categorized into two main divisions, namely:
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Carcinoid Tumors: Examples include foregut, midgut, and hindgut carcinoids.
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Pancreatic Tumors: Examples include insulinoma, gastrinoma, VIPoma, glucagonoma, somatostatinoma, and pancreatic polypeptide.
While pancreatic tumors are located in and around the pancreas and originate from the islet cell of Langerhans, carcinoid tumors usually affect the gastrointestinal and bronchial regions. When opposed to carcinoid tumors, pancreatic tumors are far less common in incidence. When it comes to radiographic features, there is no specific bias towards a specific modality. The imaging technique opted for is highly dependent on the location of the neoplasm and the skill of the clinician.
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Ultrasound is used to help with biopsy procedures or to monitor tumors that grow slowly. When attempting to obtain a clear image of gastrointestinal neuroendocrine tumors (GI NETs), endoscopic ultrasonography is the preferable method.
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The size of the tumor can be determined with a CT scan. To determine whether a tumor has migrated to the liver, a CT scan is preferred. In certain cases, a contrast medium—a unique dye—is administered prior to scanning in order to improve image detail. The patient may get this dye intravenously, orally, or as a liquid or pill to ingest. Iodinated contrast is often utilized.
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Hepatic, pancreatic, or retroperitoneal tumors can be detected with an MRI scan, either with or without the addition of gadolinium contrast agents.
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Positron emission tomography (PET scan) adopts the nuclear medicine imaging technique to obtain a detailed picture of the tumor. A tiny quantity of radioactive medication known as a tracer is put into the patient's vein during this test. The areas of the body where radioactivity has accumulated are then visible through scanning. Nonetheless, the material has too little radiation to be dangerous. Gallium Dotatate, Copper dotatate, and fluorodeoxyglucose are the most commonly used radiotracers.
How Are Neuroendocrine Tumors Treated?
Depending on the type of neuroendocrine tumor, its location, and whether the tumor exhibits symptoms of excess hormone production, the treatment options will change. Radiation therapy, targeted pharmacological therapy, peptide receptor radionuclide therapy, surgery, chemotherapy, and hormone-controlling drugs are among the general treatment possibilities. For neuroendocrine tumors that are carcinoid or pancreatic, surgical excision is the sole treatment option. On the other hand, treatment planning may use imaging in cases of non-resectable cancers. For both primary and metastatic diseases, CT (or MRI) is used to evaluate the response to treatment.
Conclusion
Receiving a neuroendocrine tumor diagnosis might be frightening and unsettling. One will eventually learn coping mechanisms to handle anxiety and discomfort. Until then, one might find it helpful to gather enough information about the illness to make decisions about required care, ask for advice from friends and family, and think about joining an online or local support group. Individuals with a similar disease might find support, encouragement, and helpful information in a support group.
