The gastrointestinal (GI) tract is part of the body's digestive system, a series of hollow, muscular organs joined in a long, twisting tube from the mouth to the anus. The digestive tract processes nutrients in foods that are eaten and helps pass waste material out of the body:
Gastrointestinal (GI) neuroendocrine tumors (also called gastrointestinal carcinoid tumors) form from a certain type of neuroendocrine cell (a type of cell that is like a nerve cell and a hormone-making cell). These cells are scattered throughout the chest and abdomen but most are found in the GI tract. Neuroendocrine cells make hormones that help control digestive juices and the muscles used in moving food through the stomach and intestines. A GI neuroendocrine tumor may also make hormones and release them into the body.
GI neuroendocrine tumors are rare and most grow very slowly. Most of them occur in the small intestine, rectum, and appendix. Sometimes more than one tumor will form.
See the following for information about other types of neuroendocrine tumors:
Anything that increases a person's chance of getting a disease is called a risk factor. Not every person with one or more of these risk factors will develop GI neuroendocrine tumors, and they can develop in people who don't have any known risk factors. Talk to your doctor if you think you may be at risk.
Risk factors for GI neuroendocrine tumors include the following:
Signs and symptoms may be caused by the growth of the tumor and/or the hormones the tumor makes. Some tumors, especially tumors of the stomach or appendix, may not cause signs or symptoms. Neuroendocrine tumors are often found during tests or treatments for other conditions.
Neuroendocrine tumors in the small intestine (duodenum, jejunum, and ileum), colon, and rectum sometimes cause signs or symptoms as they grow or because of the hormones they make. Other conditions may cause the same signs or symptoms. Check with your doctor if you have any of the following:
Signs and symptoms of GI neuroendocrine tumors in the duodenum (first part of the small intestine, that connects to the stomach) may include the following:
Signs and symptoms of GI neuroendocrine tumors in the jejunum (middle part of the small intestine) and ileum (last part of the small intestine, that connects to the colon) may include the following:
Signs and symptoms of GI neuroendocrine tumors in the colon may include the following:
Signs and symptoms of GI neuroendocrine tumors in the rectum may include the following:
The hormones made by GI neuroendocrine tumors are usually destroyed by liver enzymes in the blood. If the tumor has spread to the liver and the liver enzymes cannot destroy the extra hormones made by the tumor, high amounts of these hormones may remain in the body and cause carcinoid syndrome. This can also happen if tumor cells enter the blood. Signs and symptoms of carcinoid syndrome include the following:
These signs and symptoms may be caused by GI neuroendocrine tumors or by other conditions. Talk to your doctor if you have any of these signs or symptoms.
In addition to asking about your personal and family health history and doing a physical exam, your doctor may perform the following tests and procedures:
The prognosis and treatment options depend on the following:
Staging is the process used to find out how far the cancer has spread. The information gathered from the staging process determines the stage of the disease. The results of tests and procedures used to diagnose gastrointestinal (GI) neuroendocrine tumors may also be used for staging. See the General Information section for a description of these tests and procedures. A bone scan may be done to check if there are rapidly dividing cells, such as cancer cells, in the bone. A very small amount of radioactive material is injected into a vein and travels through the bloodstream. The radioactive material collects in the bones with cancer and is detected by a scanner.
Cancer can spread through tissue, the lymph system, and the blood:
When cancer spreads to another part of the body, it is called metastasis. Cancer cells break away from where they began (the primary tumor) and travel through the lymph system or blood.
The metastatic tumor is the same type of tumor as the primary tumor. For example, if a GI neuroendocrine tumor spreads to the liver, the tumor cells in the liver are actually GI neuroendocrine tumor cells. The disease is metastatic GI neuroendocrine tumor, not liver cancer.
For many cancers it is important to know the stage of the cancer in order to plan treatment. However, the treatment of GI neuroendocrine tumors is not based on the stage of the cancer. Treatment depends mainly on whether the tumor can be removed by surgery and if the tumor has spread.
Treatment is based on whether the tumor:
Different types of treatment are available for patients with gastrointestinal neuroendocrine (GI) tumors. Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment. Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.
Treatment of GI neuroendocrine tumors usually includes surgery. One of the following surgical procedures may be used:
Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. There are two types of radiation therapy:
Radiopharmaceutical therapy is a type of internal radiation therapy. Radiation is given to the tumor using a drug that has a radioactive substance, such as iodine I 131, attached to it. The radioactive substance kills the tumor cells.
External and internal radiation therapy are used to treat GI neuroendocrine tumors that have spread to other parts of the body.
Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping the cells from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy). When chemotherapy is placed directly into the cerebrospinal fluid, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy).
Chemoembolization of the hepatic artery is a type of regional chemotherapy that may be used to treat a GI neuroendocrine tumor that has spread to the liver. The anticancer drug is injected into the hepatic artery through a catheter (thin tube). The drug is mixed with a substance that embolizes (blocks) the artery, and cuts off blood flow to the tumor. Most of the anticancer drug is trapped near the tumor and only a small amount of the drug reaches other parts of the body. The blockage may be temporary or permanent, depending on the substance used to block the artery. The tumor is prevented from getting the oxygen and nutrients it needs to grow. The liver continues to receive blood from the hepatic portal vein, which carries blood from the stomach and intestine.
The way the chemotherapy is given depends on the type and stage of the cancer being treated.
Hormone therapy with a somatostatin analog is a treatment that stops extra hormones from being made. GI neuroendocrine tumors are treated with octreotide or lanreotide which are injected under the skin or into the muscle. Octreotide and lanreotide may also have a small effect on stopping tumor growth.
Treatment of carcinoid syndrome may include the following:
Other ways to help treat carcinoid syndrome include avoiding things that cause flushing or difficulty breathing such as alcohol, nuts, certain cheeses and foods with capsaicin, such as chili peppers. Avoiding stressful situations and certain types of physical activity can also help treat carcinoid syndrome.
For some patients with carcinoid heart syndrome, a heart valve replacement may be done.
This summary section describes treatments that are being studied in clinical trials. It may not mention every new treatment being studied. Information about clinical trials is available from the NCI website.
Targeted therapy is a type of treatment that uses drugs or other substances to identify and attack specific cancer cells. Several types of targeted therapy are being studied in the treatment of GI neuroendocrine tumors.
For information about side effects caused by treatment for cancer, visit our Side Effects page.
For some patients, taking part in a clinical trial may be the best treatment choice. Clinical trials are part of the cancer research process. Clinical trials are done to find out if new cancer treatments are safe and effective or better than the standard treatment.
Many of today's standard treatments for cancer are based on earlier clinical trials. Patients who take part in a clinical trial may receive the standard treatment or be among the first to receive a new treatment.
Patients who take part in clinical trials also help improve the way cancer will be treated in the future. Even when clinical trials do not lead to effective new treatments, they often answer important questions and help move research forward.
Some clinical trials only include patients who have not yet received treatment. Other trials test treatments for patients whose cancer has not gotten better. There are also clinical trials that test new ways to stop cancer from recurring (coming back) or reduce the side effects of cancer treatment.
Clinical trials are taking place in many parts of the country. Information about clinical trials supported by NCI can be found on NCI’s clinical trials search webpage. Clinical trials supported by other organizations can be found on the ClinicalTrials.gov website.
As you go through treatment, you will have follow-up tests or check-ups. Some tests that were done to diagnose or stage the cancer may be repeated to see how well the treatment is working. Decisions about whether to continue, change, or stop treatment may be based on the results of these tests.
Some of the tests will continue to be done from time to time after treatment has ended. The results of these tests can show if your condition has changed or if the cancer has recurred (come back).
For information about the treatments listed below, see the Treatment Option Overview section.
Treatment of gastrointestinal (GI) neuroendocrine tumors in the stomach may include the following:
For patients with GI neuroendocrine tumors in the stomach and MEN1 syndrome, treatment may also include:
Use our clinical trial search to find NCI-supported cancer clinical trials that are accepting patients. You can search for trials based on the type of cancer, the age of the patient, and where the trials are being done. General information about clinical trials is also available.
For information about the treatments listed below, see the Treatment Option Overview section.
It is not clear what the best treatment is for gastrointestinal (GI) neuroendocrine tumors in the duodenum (first part of the small intestine, that connects to the stomach). Treatment may include the following:
Treatment of GI neuroendocrine tumors in the jejunum (middle part of the small intestine) and ileum (last part of the small intestine, that connects to the colon) may include the following:
Use our clinical trial search to find NCI-supported cancer clinical trials that are accepting patients. You can search for trials based on the type of cancer, the age of the patient, and where the trials are being done. General information about clinical trials is also available.
For information about the treatments listed below, see the Treatment Option Overview section.
Treatment of gastrointestinal (GI) neuroendocrine tumors in the appendix may include the following:
Use our clinical trial search to find NCI-supported cancer clinical trials that are accepting patients. You can search for trials based on the type of cancer, the age of the patient, and where the trials are being done. General information about clinical trials is also available.
For information about the treatments listed below, see the Treatment Option Overview section.
Treatment of gastrointestinal (GI) neuroendocrine tumors in the colon may include the following:
Use our clinical trial search to find NCI-supported cancer clinical trials that are accepting patients. You can search for trials based on the type of cancer, the age of the patient, and where the trials are being done. General information about clinical trials is also available.
For information about the treatments listed below, see the Treatment Option Overview section.
Treatment of gastrointestinal (GI) neuroendocrine tumors in the rectum may include the following:
It is not clear what the best treatment is for tumors that are 1 to 2 centimeters. Treatment may include the following:
Use our clinical trial search to find NCI-supported cancer clinical trials that are accepting patients. You can search for trials based on the type of cancer, the age of the patient, and where the trials are being done. General information about clinical trials is also available.
For information about the treatments listed below, see the Treatment Option Overview section.
Distant metastases
Treatment of distant metastases of gastrointestinal (GI) neuroendocrine tumors is usually palliative therapy to relieve symptoms and improve quality of life. Treatment may include the following:
Liver metastases
Treatment of cancer that has spread to the liver may include the following:
Use our clinical trial search to find NCI-supported cancer clinical trials that are accepting patients. You can search for trials based on the type of cancer, the age of the patient, and where the trials are being done. General information about clinical trials is also available.
For information about the treatments listed below, see the Treatment Option Overview section.
Treatment of recurrent gastrointestinal (GI) neuroendocrine tumors may include the following:
Use our clinical trial search to find NCI-supported cancer clinical trials that are accepting patients. You can search for trials based on the type of cancer, the age of the patient, and where the trials are being done. General information about clinical trials is also available.
For more information from the National Cancer Institute about gastrointestinal neuroendocrine tumors, see the following:
For general cancer information and other resources from the National Cancer Institute, visit:
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PDQ® Adult Treatment Editorial Board. PDQ Gastrointestinal Neuroendocrine Tumors Treatment. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at: https://www.cancer.gov/types/gi-neuroendocrine-tumors/patient/gi-neuroendocrine-treatment-pdq. Accessed <MM/DD/YYYY>. [PMID: 26389212]
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