The endocrine system is a complex network in the human body where organs communicate with one another by secreting hormones into the bloodstream. These hormones can then stimulate or suppress the function of other nearby or distant organs, thereby ultimately playing an essential role in the “checks and balances” feedback system of the body. Hormones regulate a wide range of bodily functions, such as activities of entire organs; growth and development; reproduction; sexual characteristics; usage and storage of energy; and levels of fluid, salt, and sugar in the blood.
Gastrointestinal neuroendocrine tumors — GI-NETs or carcinoids — are uncommon organ-specific tumors of the gastrointestinal tract that can occur anywhere from the stomach to the rectum. They are different from other cancers because NETs have the ability to secrete excess hormones into the bloodstream that cause symptoms. These tumors are most frequently found in the appendix, but are increasingly recognized in the small intestine and pancreas. They are a curious family of tumors that behave differently from the more common adenocarcinomas, as well as differently from each other depending in part on where they arise.
GI-NETs have a broad spectrum of behavior that is somewhat organ-specific. NETs that arise in the appendix are almost always benign and treated by simple appendectomy, whereas those that arise in the terminal ileum are usually malignant and frequently are not identified until they have already metastasized to lymph nodes or distant organs such as liver or bone. In fact, it is not uncommon for patients to present with symptoms due to the metastases rather than the primary tumor itself. Gastric (stomach) NETs can behave very differently depending on whether they have developed secondary to other medical treatments or arisen spontaneously – the former are more likely to be indolent, whereas the latter are more likely to be malignant. Pancreatic NETs (see below) are unique in that they can be functioning or non-functioning defined by whether they secrete well-known hormones such as insulin, gastrin, vasoactive intestinal peptide, and others. Finally, NETs of the colon and rectum are often recognized on routine colonoscopy and can often be managed by endoscopic means.
Pancreatic NETs are a unique subset of tumors that have the ability to over-produce hormones (i.e. functional tumors) that are normally secreted by the human body. These include:
- Insulinoma: Secrete excess insulin, which causes extremely low blood sugar
- Gastrinoma: Secrete excess gastrin, which causes ulcers in the stomach and small intestine
- VIPoma: Secrete excess vasoactive intestinal peptide (VIP), which causes excessive watery diarrhea and subsequent severe dehydration and electrolyte disturbances
- Glucagonoma: Secrete excess glucagon, which causes high blood sugar (diabetes), rashes, blood clots, and depression
- Somatostatinoma: Secrete excess somatostatin, which causes gallstones, diarrhea, high blood sugar (diabetes), and weight loss
- Non-functional: Do not secrete any hormones, and are usually identified on imaging studies obtained for other reasons
These pancreatic tumors have a variable ability to metastasize to other organs in the body – for example, 90% of insulinomas behave in an indolent fashion and do not metastasize, whereas 75% of glucagonomas are malignant and can metastasize outside of the pancreas. Your physician at WCM will review your specific type of tumor with you, regarding its malignant potential and implications of hormone over-production.
It is important to know that neuroendocrine tumors can be non-inherited (arise sporadically) or inherited (passed along the family tree). Although rare, the most common genetically inherited conditions involving pancreatic NETs include:
- Multiple Endocrine Neoplasia type-1 (MEN1): These patients have a mutation in the MEN1 gene and can also develop pituitary and parathyroid tumors.
- Neurofibromatosis Type 1 (von Recklinghausen disease): These patients experience a constellation of symptoms including café-au-lait spots and neurofibromas on the skin, but are also at increased risk for GI-NETs, pancreatic NETs, and pheochromocytomas.
- Von Hippel-Lindau (VHL): These patients develop tumors of the central nervous system, inner ear, and kidney, but also are at increased risk for pancreatic neuroendocrine tumors and pheochromocytomas.
At WCM, patients with inherited disorders or suspicion for inherited disorders are evaluated by our geneticists for thorough evaluation and counseling.
NETs have the ability to secrete additional hormones called serotonin and kallikrein, which can a profound effect on the human body. When patients become symptomatic from this hormone over-production, Carcinoid Syndrome can result. Symptoms of this disease include:
- Abdominal pain
- Difficulty breathing (similar to an asthma attack)
- Heart valve dysfunction
- Heart failure
Carcinoid Syndrome is a rare disorder that requires prompt and thorough neuroendocrine tumor evaluation. Identification of a primary tumor is prudent, as well as evaluation for metastatic spread of the disease.
At the Weill-Cornell Endocrine Oncology center, we will provide you with cutting-edge technology and innovative procedures to diagnose and evaluate neuroendocrine tumors. Our comprehensive work up will begin with bloodwork to screen for tumor markers and relevant over-produced hormones as described above. We offer the latest radiographic imaging studies to localize NETs and evaluate for any spread of disease, including:
- Gallium-68 DOTATATE PET-CT scan
- Traditional FDG PET-CT
After we collect the pertinent information, you will be walked through the treatment process under the supervision of our world-renowned experts using a patient-centered multidisciplinary approach. At the Endocrine Oncology program, your doctor will help you choose the most appropriate treatment modality for you, which is centered on the most recent evidence-based medicine management protocols.
Many neuroendocrine tumors can be removed surgically, and here at Weill Cornell Medicine, we use minimally invasive techniques like laparoscopic surgery, robotically assisted surgery, or tumor-directed ablation that accelerates your recovery period and reduces length of stay in the hospital.
After surgery, all patients with neuroendocrine tumors are placed in a registry and followed long term. This will entail blood work and imaging studies that our staff will monitor. Typically, patients with a history of neuroendocrine tumors should have annual cross-sectional imaging studies (e.g. CT scan), as well as blood tests to look for hormones and other biochemical markers that might suggest the return of the cancer.
In specific cases, novel therapies and imaging technology provided by our physicians and scientists at our program will be used to optimize your outcome. Furthermore, several research protocols and molecular diagnostic techniques are being developed at our institution. Your doctor will discuss if you are a candidate for these protocols to more specifically diagnose and treat your neuroendocrine tumor.
At the Weill Cornell Endocrine Oncology program, we are dedicated to a patient-centered multidisciplinary approach to provide you with the most up-to-date treatment options and access to clinical trials for neuroendocrine tumors.