Neuroendocrine tumors arising outside the pancreas are most often carcinoid tumors, and represent the most common type of neuroendocrine cancer. Carcinoid tumors are considered a type of neuroendocrine tumor because they start in the hormone-producing cells of various organs — primarily the digestive tract. A carcinoid tumor can arise anywhere between the stomach and the rectum; the small intestine, appendix, and stomach are the most common sites.
Because carcinoid tumors generally grow slowly over many years, patients typically don't experience symptoms — such as diarrhea, skin flushing, and difficulty breathing — until they are quite advanced. The tumor might be discovered through a test for an unrelated disease or condition. These tumors can occur as part of certain genetic disorders — such as multiple endocrine neoplasia type 1 (MEN I) and neurofibromatosis type 1 (NF1, or von Recklinghausen disease), a disorder affecting the nervous system. Carcinoid tumors account for nearly half of all small intestine cancers.
The symptoms a person develops from a gastrointestinal carcinoid tumor often depend on where it is located. In ten percent of patients, carcinoid tumors release enough hormone-like substances into the bloodstream to cause symptoms known as "carcinoid syndrome," which is characterized by facial flushing, severe diarrhea, wheezing, and fast heartbeat. Over a long period of time, these hormone-like substances can damage heart valves, causing shortness of breath, weakness, and heart murmur. They may also cause weight gain, weakness, high blood sugar or diabetes, and increased body and facial hair.
Diagnosis of Neuroendocrine Tumors
In addition to a physical examination, endocrine oncologists at the Center for Advanced Digestive Care may use the following tests to diagnose an endocrine tumor:
The doctor may take samples of blood, urine, and stool to check for abnormal levels of hormones, glucose levels, and other substances.
To confirm a diagnosis, a small sample of the tumor is sometimes obtained for examination under a microscope using either a thin needle (fine-needle aspiration biopsy) or a wider needle (core biopsy). Sometimes, doctors will suggest a biopsy in which the tumor and possibly other tissues in the area are removed by surgery, most often done under general anesthesia.
In some cases, the doctor may evaluate a patient's central nervous system (brain and spinal cord function) by testing reflexes, motor and sensory skills, balance, and coordination.
Imaging tests can help to confirm a diagnosis and determine the exact location and size of a tumor, including whether there has been spread to other organs and whether the tumor(s) can be surgically removed. Doctors may use one or more of these tests:
- Magnetic resonance imaging (MRI)
- Triphasic computed tomography (CT) scanning
- Positron emission tomography (PET scanning)
- MIBG Scintiscan
Treatment of Neuroendocrine Tumors
The treatment of a neuroendocrine tumor depends on the type of tumor, its size and location, whether it is benign or malignant, whether the cancer has spread, and the patient's overall health. The Center for Advanced Digestive Care assesses each patient to create a personalized plan of care for neuroendocrine tumor treatment. Our multidisciplinary team of endocrine specialists works with patients to determine the best approach. Treatment may consist of one or more of the following therapies:
Surgical removal of the tumor is the first treatment for many neuroendocrine tumors. We specialize in image-guided minimally invasive surgical approaches that reduce the length of inpatient hospital stays, result in less physical trauma, and help patients resume normal activities as soon as possible.
Hormone therapy may be given to help stop the tumor from growing, or to relieve symptoms caused by the tumor by lowering the levels of hormones in the body. Patients with gastrointestinal carcinoid tumors that cannot be surgically removed may benefit from injections of a synthetic hormone which controls hormone-related symptoms and may have the potential to slow tumor growth.
Systemic chemotherapy, delivered through the bloodstream, employs drugs to kill cancer cells. For patients with gastrointestinal carcinoid tumors, chemotherapy is usually reserved for patients whose tumors begin to grow during treatment with a synthetic hormone. In addition, chemotherapy may be used to treat advanced neuroendocrine tumors that contain fast-growing cells.
Liver Tumor Embolization
Embolization is a localized approach to destroying liver tumors that may be used to treat gastrointestinal carcinoid tumors that spread to the liver. Embolization uses image guidance, such as CT or ultrasound, to inject tiny particles through a small tube (catheter) threaded into the hepatic artery. The particles block the flow of blood to the tumor, depriving it of the nutrients and oxygen it needs to survive. Embolization may be used alone or in combination with surgery.
Some patients with neuroendocrine tumors benefit from radiation therapy, which uses a type of energy called ionizing radiation to kill cancer cells and shrink tumors. The goal is to kill as many cancer cells as possible without harming healthy tissue.
Immunotherapy is designed to boost the body's natural defenses to fight the cancer. It uses materials made either by the body or in a laboratory to bolster, target, or restore the ability of the immune system to recognize and destroy cancer cells.
This treatment targets faulty genes or proteins that contribute to cancer growth and development. Early results of clinical trials with targeted drugs for the treatment of neuroendocrine tumors are promising, but additional research is needed to confirm their effectiveness.
NewYork-Presbyterian Hospital has established a clinical trials network to ensure that patients have access to medicines and therapies that are on the cutting edge. Clinical trials take place under the most stringent guidelines, and those who participate benefit from closely supervised monitoring. Patients are encouraged to speak with their doctors about current clinical trials for neuroendocrine tumors when making their treatment plan decisions.