Neuroendocrine Tumours (NETs)

Diagnosis

The diagnosis of NETs is made through the following methods:

• Medical history and physical examination: The symptoms of the NETs vary widely and overlap with those of certain more common conditions. However, patients should not ignore these symptoms and consult with their physicians to rule out the presence of more serious underlying diseases. The patients are thoroughly evaluated for their symptoms and are enquired about their initiation, severity, and progression. The patients are also asked about their habits of smoking and consuming alcohol as they increase the risk of NETs. The medical history of patients is also evaluated as certain conditions, such as diabetes, chronic atrophic gastritis, multiple endocrine neoplasia, and neurofibromatosis-1, increase the risk of NETs. The family history of the patients also plays a role in the development of NETs.
• Blood tests: These are usually performed to determine the overall health status of the patients. As one of the symptoms of NETs is rectal bleeding, the cancer specialist may check the level of red blood cells to detect anemia through blood tests. The patients may also undergo electrolyte panel tests to determine the level of various electrolytes in the blood. In addition, the level of glucose is also determined to ascertain if the patient has diabetes, Cushing syndrome, or pancreatic abnormalities.
• Biochemical markers: NETs increase hormone levels and certain other substances in the blood and urine. Detecting these biomarkers help in the diagnosis of NETs. The biomarkers include 5-HIAA, chromogranin-A, gastrin, cortisol, insulin, glucagon, calcitonin, serotonin, somatostatin, metanephrines, and ACTH.
• Ultrasound: Ultrasound is usually performed for abnormalities in the abdominal region. The patients are recommended an ultrasound to check for the presence of a tumor or other diseases causing the symptoms. Further, the patients may also have an echocardiogram to determine the effect of carcinoid syndrome on the heart.
• CT scan: CT scan involves using X-rays to detect the presence of a tumor in the pelvis, abdomen, and chest. It also provides information about the spread of the tumor to other organs, such as the liver.
• MIBG scan: MIBG scan is performed if the patients are suspected of having specific tumors, such as pheochromocytoma. A substance, metaiodobenzylguanidine (MIBG), is injected into the body during this test. Once the substance is circulated in the body, the patients undergo a full-body scanner. The images obtained show the collection of MIBG at particular sites.
• PET scan: PET scan uses radioactive substances taken up by the tumor cells. When accumulated in the tumor cells, these substances are detected by performing a complete body scan of the patients.
• Octreotide scan: In the octreotide scan, the patient receives intravenous radiolabelled somatostatin analogues. These analogues are accumulated in the NETs. They emit radiations, which is detected by the tracer device. 111in-labeled pentetreotide somatostatin receptor imaging has a sensitivity of 71% for NETs of bronchi, 46-83% for NETs of the pancreas, and 46-100% for NETs of the abdomen.
• Bone scan: A bone scan is performed to detect the spread of NETs to the bone. It involves the use of radioactive substances accumulated in the abnormal cells in the bone.
• Endoscopy: Endoscopy is also performed to check the cause of symptoms. The type of endoscopy depends upon the area to be examined. Colonoscopy examines the large intestine, while upper GI endoscopy evaluates the stomach, esophagus, and initial section of the small intestine. The health of the lungs is checked through bronchoscopy.
• Barium swallow test: The barium swallow test involves using a barium solution. When the patients swallow barium liquid, it forms a layer in the gastrointestinal tract. X-ray is then used to obtain images of the upper part of the GI tract. These images are analyzed for any surface abnormality.
• Biopsy: Biopsy is the procedure that involves taking samples of abnormal tissues and checking them in the laboratory for the presence of cancer cells. The techniques used for biopsy are core biopsy, fine needle aspiration, and endoscopic biopsy.