Neuroendocrine tumors (NETs), sometimes referred to as carcinoids, are abnormal growths that begin in the neuroendocrine cells, which are distributed widely throughout the body. While some features of NETs are unique to the site of origin, other characteristics are shared, regardless of site.
Types of neuroendocrine tumors
Various types of neuroendocrine tumors can occur in many places in the body and grow differently. Many NETs first appear in the lungs or the gastrointestinal tract, including the stomach, pancreas, appendix, intestines, colon and rectum. NETs may also appear in the thymus, thyroid gland, adrenal gland and pituitary gland.
NETs may be classified by the site of origin. Doctors may use terms such as “GI NET,” “pancreatic NET” or “lung NET” to describe the tumor. Although NETs vary in size and how quickly they grow, almost all NETs are considered to be malignant, or cancerous.
Incidence of NETs
Although NETs comprise less than 2 percent of GI malignancies, these tumors are actually more prevalent than stomach and pancreatic cancers combined. Surveillance Epidemiology and End Results (SEER) data from the National Cancer Institute (NCI) shows a five-fold increase in the incidence of neuroendocrine tumors from 1973 to 2004. As predicted, the incidence of NETs has continued to rise and has markedly increased over the past 15 years.
< Symptoms of neuroendocrine tumors
Different types of NETs cause different symptoms, depending on the location of the tumor, and whether the NET is functional or nonfunctional. Functioning NETs are defined based upon the presence of clinical symptoms due to excess hormone secretion by the tumor. Nonfunctional NETs do not secrete hormones. They may produce symptoms caused by the tumor’s growth.
The following are some common symptoms of NETs:
* Flushing (redness, warmth) in the face or neck without sweating
* Diarrhea, including at nighttime
* Shortness of breath, rapid heartbeat/palpitations
* High blood pressure
* Fatigue, weakness
* Abdominal pain, cramping, feeling of fullness
* Unexplained weight gain or loss
* Wheezing, coughing
* Swelling in the feet and ankles
* Skin lesions, discolored patches of skin, thin skin
* High blood glucose levels (frequent urination, increased thirst, increased hunger)
* Low blood glucose levels (shakiness, dizziness, sweating, fainting)
NETs often don’t cause symptoms early in the disease process. When symptoms are present, they may be similar to those caused by more common conditions. As a result, NETs are sometimes misdiagnosed as irritable bowel syndrome (IBS). However, with IBS, abdominal discomfort is usually relieved by going to the bathroom.
Since most NET patients are diagnosed at a late stage, it’s important to let your doctor know if you notice new or persisting symptoms or changes in your body.
Stages of neuroendocrine tumors
Identifying the stage of disease is an important step in planning the appropriate treatment for neuroendocrine tumors. NETs may:
* Be contained in a particular area of the body (localized)
* Have spread to nearby tissues or lymph nodes (regional)
* Have spread throughout the body (metastatic)
More than 50 percent of NETs have already spread to other parts of the body by the time they are diagnosed. NETs metastasize most often to the liver, peritoneal cavity or bone.
Neuroendocrine tumors are staged according to the TNM staging system: tumor (T), node (N), metastasis (M). The World Health Organization (WHO) classifies neuroendocrine tumors according to the malignant potential of the tumor:
Well-differentiated neuroendocrine tumors (grade 1 and 2)
Poorly-differentiated neuroendocrine tumors (grade 3)
Diagnosing neuroendocrine tumors
There are many types of neuroendocrine tumors, and each requires a different approach to diagnosis and treatment. Diagnosis of NETs depends on the type of tumor, its location, whether it produces excess hormones, how aggressive it is, and whether it has spread to other parts of the body.
Our cancer experts use state-of-the-art diagnostic tools to evaluate the disease and plan your individualized treatment. The following are some diagnostic tests we may use to diagnose NETs:
* Lab tests, cytopathology
* Biopsy, endoscopic ultrasound
* CT scan, CT angiography
* Nuclear medicine imaging
* Genetic testing and counseling
Integrative care for patients with neuroendocrine tumors
Once a diagnosis is made, your care team will work with you to develop a comprehensive NET treatment plan based on your unique diagnosis and needs. Since most NET patients are diagnosed at a late stage, an integrative approach is key to your well-being.
Treatment for NETs varies, depending on factors such as the type and stage of NET. The following are some common treatment options for neuroendocrine tumors:
Surgery: Surgical removal of the primary tumor is often the first option for patients with localized NETs. The goal of surgery is to fully remove a neuroendocrine tumor or reduce the tumor burden. Surgery may also be an option for those with advanced disease, to help relieve symptoms. Some surgical procedures for NETs include debulking or cytoreductive surgery, minimally invasive laparoscopic resections and liver transplantation.
Medical oncology: Depending on the type of NET and treatment goals, chemotherapy, hormone therapy and/or targeted therapy may be used to manage certain types of NETs, including advanced NETs. Some targeted therapies for pancreatic NETs include everolimus and sunitinib. Chemoembolization, in which chemotherapy drugs are administered directly into the tumor, may be an option if the disease has metastasized to the liver.
Radiation oncology: Radiation therapy is generally used when a neuroendocrine tumor has spread or is in a location that makes surgery difficult. CyberKnife® is a non-invasive option for patients and enables our radiation oncologists to deliver high, targeted doses of radiation to NETs. For metastatic disease to the liver, TheraSphere® or SIR-Spheres® is an innovative therapy that delivers radiation directly to tumors in the liver.
Interventional radiology: Radiofrequency ablation may be used for NETs that have spread to the liver. This technique uses high-energy radio waves to heat and destroy cancerous cells. NanoKnife® provides a minimally invasive option for patients with inoperable or difficult-to-reach tumors. Instead of using extreme heat or cold, which may damage normal adjacent tissues, the NanoKnife System uses electrical currents to destroy NETs. For NETs that have spread to the liver, embolization procedures may help reduce or cut off the supply of blood to the tumor.
Gastrointestinal procedures: We provide a full range of treatment options for gastrointestinal NETs. The team uses innovative technologies to look at the GI tract in different and minimally invasive ways. We may apply innovative techniques and ablative treatments to help remove obstructions in the GI tract and relieve pain or breathing problems.
Pain management: Pain management and palliative care are important for patients with NETs. Throughout your treatment, the pain management team is on call 24/7 to help you anticipate and proactively manage pain. We’ll help you get comfortable and help you manage the side effects of pain medication, such as nausea, drowsiness and constipation. The goal is to find a balance between controlling pain and preserving quality of life.
Nutrition therapy: Nutrition is a key factor during NET treatment. These tumors, particularly gastrointestinal NETs, may affect the body’s ability to digest and absorb vital nutrients from food, putting patients at risk for malnutrition. Symptoms may include nausea, taste changes, weight loss, fatigue, decreased appetite, fullness, pain, gas, diarrhea and constipation. Our nutrition therapy team is available to offer strategies designed to help you stay strong and nourished to help you avoid treatment delays or interruptions. Your personalized nutrition therapy goals will likely include preventing or reversing poor nutrition, managing nutrition-related symptoms, and maintaining or improving weight and strength. Some NET patients are also at risk for diabetes and glucose intolerance. To decrease complications of diabetes, our dietitians may recommend options to help you manage blood sugar levels throughout your care.
Naturopathic medicine: Throughout your NET treatment, you may experience symptoms or discomfort after eating, which may interfere with your ability to digest nutrients and fat-soluble vitamins. Our naturopathic clinicians are available to work with your oncologists to recommend a variety of supplements and botanicals designed to offer upper GI support. Naturopathic therapies may also help you manage endocrine and blood sugar abnormalities, digest your food more easily and better absorb nutrients. Naturopathic therapies may also help to prevent and treat nausea, and reduce acid reflux, heartburn, bloating, gas and diarrhea.