Gastrointestinal carcinoid tumors are a type of cancer that forms in the lining of the gastrointestinal (GI) tract. Cancer starts when cells begin to grow out of control. Cells in nearly any part of the body can become cancer. To learn more about what cancer is and how it can grow and spread, see What Is Cancer?

To understand gastrointestinal carcinoid tumors, it helps to know about the gastrointestinal system, as well as the diffuse neuroendocrine system.

The gastrointestinal system

The gastrointestinal (GI) system, also known as the digestive system, processes food for energy and rids the body of solid waste. After food is chewed and swallowed, it enters the esophagus. This tube carries food through the neck and chest to the stomach. The esophagus joins the stomach just beneath the diaphragm (the breathing muscle under the lungs). The stomach is a sac-like organ that holds food and begins the digestive process by secreting gastric juice. The food and gastric juices are mixed into a thick fluid, which then empties into the small intestine.

Survival rates are often used by doctors as a standard way of discussing a person's prognosis (outlook). Some people with cancer may want to know the survival statistics for people in similar situations, while others may not find the numbers helpful, or may even not want to know them. Stop reading here and go to another section if you decide that you do not want to know them.

The 5-year survival rate refers to the percentage of patients who live at least 5 years after their cancer is diagnosed. Of course, many people live much longer than 5 years (and many are cured). Also, people who have this cancer can die from something else. These survival rates, called observed survival rates, do not take this into account.

To get 5-year survival rates, doctors have to look at people who were treated at least 5 years ago. Improvements in treatment since then may result in a better outlook for people now being diagnosed with carcinoid tumors.

Survival rates are often based on previous outcomes of large numbers of people who had the disease, but they can’t predict what will happen in any particular person’s case. Many other factors can affect a person’s outlook, such as treatment received, the grade of the tumor and its growth rate, and the patient’s age and health. Your doctor can tell you how the numbers below may apply to you, as he or she is familiar with your situation.

Most GI carcinoid tumors are found while they are still localized, but this varies based on the organ they start in. Tumors of the stomach, duodenum (the first part of the small intestine), appendix, and rectum are likely to be found before they have spread. In contrast, many tumors of other parts of the small intestine (the jejunum/ileum) and the colon (including the cecum) have already spread to nearby tissues or lymph nodes or to distant sites when they are first diagnosed.

The following 5-year survival rates are based on people diagnosed with carcinoid (well and moderately-differentiated neuroendocrine tumors) between 1988 and 2004:

5-year observed survival rates for carcinoid tumors

*The 5-year survival for these tumors at the regional stage is slightly better than for the localized stage, although the reason for this is not exactly clear.

There is always research going on in the field of gastrointestinal (GI) carcinoids. Scientists keep looking for the causes of, ways to prevent, and new approaches to diagnose and treat GI carcinoid tumors.

Genetics

Researchers are looking for the causes of GI carcinoid tumors in the hope that this knowledge can be used to help prevent or treat them in the future. A great deal of progress has been made in recent years. For example, scientists have found that changes in the MEN1 gene (the gene that causes multiple endocrine neoplasia, type 1) are seen in many people with GI carcinoids. Other genetic changes that seem to make tumors more aggressive are now being explored as well.

Diagnosis and staging

Because the outlook and treatment of GI carcinoid tumors and other cancers of the digestive tract are very different, accurate diagnosis is important. Researchers have made great progress in developing tests that can detect specific substances found in the cells of carcinoid tumors. Most of these tests treat tissue samples with special antibodies made in the lab. The antibodies are designed to recognize specific substances that appear only in certain types of tumors.

OctreoScan^® is an imaging test commonly used to look for GI carcinoid tumors in the body. Researchers are now looking at other radionuclide methods to see if they can detect carcinoid tumors early.

Treatment

Surgery is the main treatment option for carcinoid tumors when possible. But better approaches are needed when surgery can’t remove all of the tumors. Chemotherapy has had limited success. New chemotherapy drugs and combinations of drugs are being studied, but true advances are likely to come from other approaches.

Targeted therapy

Several newer types of drugs, known as targeted therapies, are now being studied for use against neuroendocrine tumors. Targeted therapy uses drugs or other substances to identify and attack cancer cells while doing little damage to normal cells. These therapies attack the parts of cancer cells that make them different from normal, healthy cells. Each type of targeted therapy works differently, but all alter the way a cancer cell grows, divides, repairs itself, or interacts with other cells.

Everolimus (Afinitor^®) is a targeted drug that works by blocking a cell protein known as mTOR, which normally helps cells grow and divide. It is approved by the FDA to treat advanced pancreatic neuroendocrine tumors. It is also being studied to see if it can help patients with GI carcinoids. In one study, adding everolimus to octreotide (Sandostatin) was better than octreotide alone in halting tumor growth.

Bevacizumab (Avastin^®) is a type of targeted drug that attacks a tumor’s blood supply. It is already being used against some types of cancer and is being studied for carcinoid tumors.

Other targeted therapies block the molecules that increase the growth of cancer cells. Some of these (such as erlotinib, temsirolimus, and sorafenib) are used in other types of cancer and are now being tested against carcinoids.

Netazepide is new drug that blocks the hormone gastrin. In early studies of patients who have carcinoid tumors of the stomach and high gastrin levels, this drug helped the tumors shrink. More studies are planned.

Radionuclide scans, such as the I-131 MIBG scan, can help find neuroendocrine tumors because they use substances that are attracted to neuroendocrine cells. These substances are attached to slightly radioactive elements so that they can be detected with special cameras. Using higher doses of I-131 MIBG delivers more radiation to the tumor cells and is used in Europe to treat neuroendocrine tumors and cancers. But doctors are now studying the use of a form of octreotide (or a similar drug called edotreotide) that has been attached to a radioactive form of the element yttrium called 90-Y. When injected into the body, the drug homes in on the tumor cells, allowing the radiation from the 90-Y to kill them. So far, results have been promising, but this approach is still only available in the United States as a part of a clinical trial.

If you have symptoms that might be from a gastrointestinal (GI) carcinoid tumor, you should see a doctor. He or she will take your medical history and examine you. If the doctor suspects some type of tumor or cancer, some tests will be ordered.

Medical history and physical exam

In taking your medical history, the doctor asks you questions about your general health, lifestyle habits, symptoms, and risk factors. The doctor also will probably ask about symptoms of the carcinoid syndrome, as well as symptoms that might be caused by a mass (tumor) in the stomach, intestines, or rectum.

Some patients with neuroendocrine tumors also have cancers or benign tumors of other organs, so doctors may ask about symptoms that might suggest other tumors are present. A thorough physical exam will provide information about signs of neuroendocrine tumors and other health problems. The doctor may pay special attention to the abdomen, looking for a tumor mass or enlarged liver.

If your medical history and physical exam give the doctor reason to suspect you might have a GI carcinoid, some tests will be ordered to find out if the disease is present.

Imaging tests

Your doctor may order one or more types of imaging tests to help determine the cause of your symptoms.

Barium x-ray

These tests use a barium-containing solution that coats the lining of the esophagus, stomach, and intestines. The coating of barium helps show abnormalities of the lining of these organs. This type of study is often useful in diagnosing some GI carcinoid tumors. It is least effective in finding small intestine carcinoids.

Barium studies can be used to examine the upper or lower parts of the digestive system. You will probably not be able to eat or drink anything (other than water) the night before the test. If the colon is being examined, you may need to take laxatives and/or enemas to cleanse the bowel the night before or the morning of these exams.

Barium swallow: This test is used to examine the lining of the esophagus. The patient drinks a barium solution that coats the lining of the esophagus. Then x-ray pictures are taken.

Upper GI series: This test is used to examine the lining of the stomach and the first part of the small intestine. The patient swallows the barium solution, and then may be moved around a bit so that it coats the inside of the stomach. Over time, it will leave the stomach and coat the first part of the small intestine. More x-rays can be taken over the next few hours as the barium travels through the rest of the small intestine. This is called a small bowel follow-through.

Enteroclysis: This is another way to look at the small intestine. In this test, a thin tube is passed from the mouth or nose down through the stomach to the start of the small intestine. Barium contrast is sent through the tube, along with a substance that creates more air in the intestines, causing them to expand. X-rays of the intestines are then taken. This test may be quicker and give clearer images of the small intestine than a small bowel follow-through, but the use of a tube to give the barium makes it more uncomfortable.

Barium enema: This test (also known as a lower GI series) is used to look at the inner surface of the colon and rectum. The barium solution is given as an enema (through the anus) while the patient is lying on the x-ray table. When the colon is about half full of barium, the patient rolls over so the barium spreads throughout the colon. Then x-rays are taken. After the barium is put in, air may be blown in to help spread the barium toward the bowel wall and better coat the inner surface. This is called an air contrast (or double contrast) barium enema. X-rays are then taken.

Barium x-rays are used less these days than in the past. In many cases they are being replaced by endoscopy, where the doctor actually looks into the esophagus, stomach, or colon with a narrow fiber optic scope.

Computed tomography (CT) scan

A CT scan can help tell if the cancer has spread into your lymph nodes or other organs such as your liver.

The CT scan uses x-rays to make detailed cross-sectional images of your body. Instead of taking one picture, like a regular x-ray, a CT scanner takes many pictures as it rotates around you. A computer then combines these into images that look like slices of the part of your body that is being studied.

Before any pictures are taken, you might be asked to drink 1 to 2 pints of a liquid called oral contrast. This helps outline the intestine so that certain areas are not mistaken for tumors. You might also receive an IV (intravenous) line through which a different kind of contrast dye (IV contrast) is injected. This helps better outline structures in your body. The injection can cause some flushing (redness and warm feeling that may last hours to days). A few people are allergic to the dye and get hives. Rarely, more serious reactions like trouble breathing and low blood pressure can occur. Medicine can be given to prevent and treat allergic reactions. Be sure to tell the doctor if you have any allergies (especially to iodine or shellfish) or if you have ever had a reaction to any contrast material used for x-rays.

A CT scanner has been described as a large donut, with a narrow table that slides in and out of the middle opening. You will need to lie still on the table while the scan is being done. CT scans take longer than regular x-rays, and you might feel a bit confined by the ring while the pictures are being taken.

When GI carcinoid tumors spread, it is often to the liver. To see if there are areas of cancer spread in the liver, a special type of CT known as a 3D-, 4D-, or multiphase CT scan is done. This means having one set of CT images taken before IV contrast is given. Then more sets of scans are taken as the contrast passes through the liver.

CT scans can also be used to guide a biopsy needle precisely into a suspected area of cancer spread. For a CT-guided needle biopsy, you remain on the CT scanning table, while a doctor moves a biopsy needle through the skin and toward the mass. CT scans are repeated until the doctor is sure that the needle is in the mass. A fine-needle biopsy sample (tiny fragment of tissue) or a core-needle biopsy sample (a larger cylinder of tissue) is removed and looked at under a microscope.

Magnetic resonance imaging (MRI) scan

MRI scans use radio waves and strong magnets instead of x-rays to create detailed images of parts of the body. Like a CT scan, an MRI produces cross-sectional slices of the body. As with a CT scan, a contrast material might be injected into a vein, but it is not needed as often.

MRI scans take longer than CT scans, often up to an hour. You may have to lie inside a narrow tube which can feel confining and can upset people with a fear of enclosed spaces. Special, open MRI machine can help with this if needed, although the images might not be as sharp in some cases. The MRI machine makes loud buzzing noises, but some places provide headphones to help block the sound.

Sometimes MRI is used to look at blood vessels in the liver. This requires IV contrast and is known as MR angiography (MRA).

Radionuclide scans

Scans using small amounts of radioactivity and special cameras can be helpful in looking for carcinoid tumors. They can help determine the extent of the tumor, as well as help locate it if doctors aren’t sure where it is in the body.

Somatostatin receptor scintigraphy (OctreoScan^®): This is the scan most often used to look for carcinoid tumors. For this scan, a radioactive substance called indium-111 is bound to a hormone-like substance called octreotide. When a small amount of this combined substance is injected into the blood, the octreotide causes it to attach to proteins on carcinoid cells. About 4 hours after the injection, a special camera can be used to show where the radioactivity has collected in the body. More scans may be done over the next few days as well.

I-131 MIBG scan: This is another test that can be used to find carcinoid tumors, but it is used less often than the OctreoScan. This test uses a chemical called MIBG that has radioactive iodine (I-131) attached. This substance is injected into a vein, and the body is scanned several hours or days later with a special camera to look for areas that picked up the radioactivity. These would most likely be carcinoid tumors, although other kinds of neuroendocrine tumors will also pick up this chemical.

Positron emission tomography (PET) scan

A PET scan is another imaging test that uses low levels of radioactivity to look for tumors. PET scans usually use a form of radiolabeled glucose (sugar) to find tumors. But to look for neuroendocrine tumors/cancers, a special type of PET scan is done, using a radioactive form of 5-hydroxytryptophan (5-HTP). This chemical is injected into the bloodstream and is taken up and used by carcinoid cells. After about an hour, a special camera is used to find the areas of radioactivity. Some doctors have found this type of PET scan to be more accurate than CT scans for detecting spread of disease. However, this type of PET scan is not available in every hospital (even some hospitals that have a PET scanner).

Endoscopy

Endoscopy tests use a flexible lighted tube (endoscope) with a video camera on the end. The camera is connected to a monitor, which lets the doctor see any abnormal areas in the lining of the digestive organs clearly. If needed, small pieces of the abnormal areas can be removed (biopsied) through the endoscope. The biopsy samples can be looked at under the microscope to find out if cancer is present and what kind of cancer it is.

Upper endoscopy

This test is also known as esophogogastroduodenoscopy or EGD. An endoscope is passed down through the mouth to look at the esophagus, stomach, and first part of the small bowel.

An upper endoscopy may be done in a hospital outpatient department, clinic, or doctor’s office. It usually takes 15 to 30 minutes, and most patients are given intravenous medicine to make them feel relaxed and sleepy. If you are sedated for the procedure, you will need someone to take you home (not just a cab).

Colonoscopy

This test is also called lower endoscopy. A special endoscope known as a colonoscope is inserted through the anus up into the colon. The doctor will be able to see the lining of the entire rectum and colon. For a clear view though, the colon must be completely cleaned out before the test. There are different ways to do this, but the most common is drinking a large amount of a laxative solution the night and the morning of the exam.

You will be given intravenous medicine to make you feel relaxed and sleepy during the procedure. A colonoscopy can be done in a hospital outpatient department, clinic, or doctor's office. It usually takes 15 to 30 minutes, although it may take longer if a tumor is seen and/or a biopsy is taken. Because you will be sedated for the procedure, you will need someone you know to take you home afterward.

Proctoscopy

Proctoscopy can be used to look for a rectal tumor. This test uses a shorter, rigid, hollow tube (a proctoscope), which is about 10 inches long and about 1 inch across and may have a light on the end of it. The doctor coats the proctoscope with a lubricant and then gently pushes it into the anus and rectum. By shining a light into this tube, the doctor has a clear view of the lining of the rectum and anus. This test usually requires that you take laxatives or have an enema beforehand to make sure the bowels are empty.

Capsule endoscopy

Unfortunately, neither upper nor lower endoscopy can reach all areas of the small intestine, where many carcinoid tumors begin. A technique known as capsule endoscopy may help in some cases.

This test doesn’t really use an endoscope. Instead, the patient swallows a capsule (about the size of a large vitamin pill) that contains a light source and a tiny camera. Like any other pill, the capsule goes through the stomach and into the small intestine. As it travels (usually over about 8 hours), it takes thousands of pictures. These images are transmitted electronically to a device worn around the person’s waist, while he or she goes on with normal daily activities. The pictures can then be downloaded onto a computer, where the doctor can watch them as a video. The capsule passes out of the body during a normal bowel movement and is discarded.

Double balloon enteroscopy

This is another way to look at the small intestine. The small intestine is too long (20 feet) and has too many curves to be examined well with regular endoscopy. This method gets around these problems by using a special endoscope that is made up of 2 tubes, one inside the other. First the inner tube, which is an endoscope, goes forward about a foot, and then a balloon at its end is inflated to anchor it. Then the outer tube goes forward to near the end of the inner tube and it is then anchored in place with a balloon. This process is repeated over and over, letting the doctor see the intestine a foot at a time.

This procedure is done after the patient is given drugs to make him or her sleepy and may be even done under general anesthesia (where the patient is asleep). The main advantage of this test over capsule endoscopy is that the doctor can take a biopsy if something abnormal is seen. As with other tests that are done under sedation, you will need someone to take you home after this procedure (not just a cab).

Endoscopic ultrasound (EUS)

This test uses an endoscope with a small ultrasound probe on the end. This probe releases sound waves and then uses the echoes that bounce back to create images of the digestive tract wall (or nearby lymph nodes). Putting the ultrasound probe on the end of an endoscope lets it get very close to a tumor. Because the probe is close to the area being looked at, it can make very detailed pictures.

EUS can be used to see how deeply a tumor has grown into the wall of the esophagus, stomach, intestine, or rectum. It can also help see if certain lymph nodes are enlarged and help a doctor guide a needle into lymph node, tumor, or other suspicious area to do a biopsy. You will be sedated for this test, so you will need someone to take you home (not just a cab).

Biopsy

Even if an imaging test finds a mass, it can’t tell if the mass is a carcinoid tumor, some other type of tumor, or an area of infection. The only way to know for sure is to remove cells from the abnormal area and look at them under a microscope. This procedure is called a biopsy.

There are several ways to take a sample from a GI tumor. One way is through the endoscope. When a tumor is found, the doctor can use biopsy forceps (pincers or tongs) through the tube to take a small sample of it. Another way to sample a tumor is with a CT-guided needle biopsy, as described in the section on CT scans.

Bleeding after a biopsy of a GI carcinoid is a rare but potentially serious problem. If serious bleeding occurs, doctors can sometimes inject drugs into the tumor to constrict blood vessels and slow or stop bleeding.

In rare cases, neither endoscopic biopsy nor a CT-guided needle biopsy will be able to get enough tissue to identify the type of tumor. This is sometimes the case with tumors in the small intestine. In such cases, surgery may be needed to remove a tissue sample.

You can read more about biopsies and how they are tested in Testing Biopsy and Cytology Specimens for Cancer.

Blood and urine tests

Blood and urine tests can be very helpful in diagnosing carcinoid syndrome in patients who have symptoms that might be caused by it.

Many carcinoid tumors, especially those in the small intestine, make serotonin (also called 5-HT). It is probably the cause of at least some of the symptoms of carcinoid syndrome. The body breaks it down into 5-hydroxyindoleactic acid (5-HIAA), which is released into the urine. A common test to look for carcinoid syndrome measures the levels of 5-HIAA in a urine sample collected over 24 hours. Measuring the serotonin levels in the blood may also give useful information. These tests can help diagnose many (but not all) carcinoid tumors. Sometimes, the tumors are small and don’t release enough serotonin for a positive test result.

In other cases, the tumors do not make much serotonin, but they do make its precursor, 5-HTP, which can be converted to serotonin in the urine. In patients with these tumors, the blood serotonin level may be normal, but the urine levels of serotonin and 5-HTP are high.

Some foods, including bananas, plantains, kiwi fruit, certain nuts, avocado, tomatoes, and eggplant, contain a lot of serotonin and can raise 5-HIAA levels in the urine. Medicines, including cough syrup and acetaminophen (Tylenol), can also affect the results. Ask your doctor what you should avoid before having urine or blood tests for carcinoids.

Other common tests to look for carcinoids include blood tests for chromogranin A (CgA), neuron-specific enolase (NSE), substance P, and gastrin. Medicines that lower stomach acid called proton-pump inhibitors (such as omeprazole/Prilosec^®, lansoprazole/Prevacid^®, esomeprazole/Nexium^®, and many others) can make CgA and gastrin levels high even when carcinoid tumors aren’t present. If you take any of these medicines, talk to your doctor about what you need to avoid before having these blood tests. Depending on the tumor’s location and your symptoms, your doctor might do other blood tests as well.

Some of these tests can also be used to show how well treatment is working, since the levels of these substances tend to go down as tumors shrink.

Most gastrointestinal (GI) carcinoids grow slowly. If they do cause symptoms, they tend to be vague. When trying to figure out what’s going on, doctors and patients are likely to explore other, more common possible causes first. This can delay a diagnosis, sometimes even for several years. But some do cause symptoms that lead to their diagnosis.

Symptoms by location of the tumor

The symptoms a person develops from a GI carcinoid tumor often depend on where it is.

The appendix

People with tumors in their appendix often don’t have symptoms. If it is discovered, it is usually when they have their appendix removed during an operation for some other problem. Sometimes, the tumor blocks the opening between the appendix and the rest of the intestine and causes appendicitis. This leads to symptoms like nausea, vomiting, and abdominal (belly) pain.

The small intestine or colon

If the tumor starts in the small intestine, it can cause the intestines to kink and be blocked for a while. This can cause cramps, belly pain, weight loss, fatigue, bloating, diarrhea, or nausea and vomiting, which might come and go. This can sometimes go on for years before the carcinoid tumor is found. A tumor usually needs to grow fairly large before it completely blocks (obstructs) the intestine. When that happens, patients have severe belly pain, nausea and vomiting.

Sometimes a carcinoid tumor can block the opening of the Ampulla of Vater, which is where the common bile duct (from the liver) and the pancreatic duct (from the pancreas) empty into the intestine. When this is blocked, bile can back up, leading to yellowing of the skin and eyes (jaundice). Pancreatic juices can also back up, leading to an inflamed pancreas (pancreatitis), which can cause belly pain, nausea, and vomiting.

Sometimes, a carcinoid can cause intestinal bleeding. This can lead to anemia (too few red blood cells) with fatigue and shortness of breath.

The rectum

Rectal carcinoid tumors are often found during routine exams, even though they can cause pain and bleeding from the rectum and constipation.

The stomach

Carcinoid tumors that develop in the stomach usually grow slowly and often do not cause symptoms. They are sometimes found during an exam of the stomach by an endoscopy looking for other things. (Endoscopy is described later in this section.) Some can cause symptoms such as the carcinoid syndrome.

Signs and symptoms from hormones made by carcinoid tumors

Some carcinoid tumors can release hormones into the bloodstream. This can create different problems depending on which hormones are released.

Carcinoid syndrome

About 1 out of 10 carcinoid tumors release enough hormone-like substances into the bloodstream to cause the symptoms of carcinoid syndrome. These include:

• Facial flushing (redness and warm feeling)
• Severe diarrhea
• Wheezing
• Fast heartbeat

Many people find that factors such as stress, heavy exercise, and drinking alcohol trigger these symptoms. Over a long time, these hormone-like substances can damage heart valves, causing shortness of breath, weakness, and a heart murmur (an abnormal heart sound).

Not all GI carcinoids cause the carcinoid syndrome. For example, rectal carcinoids usually do not make the hormone-like substances that cause these symptoms.

Most cases of carcinoid syndrome occur only after the cancer has already spread to other parts of the body. Normally, blood coming from the GI tract first flows through the liver, where substances made by GI carcinoid tumors are broken down before they can reach the rest of the body. This prevents carcinoid symptoms. But if the cancer spreads outside the intestine (such as to the liver or lungs), the substances it makes can enter the main bloodstream and reach other parts of the body, where it can cause symptoms.

Cushing syndrome

Some neuroendocrine tumors produce ACTH (adrenocorticotropic hormone), a substance that causes the adrenal glands to make too much cortisol. This can cause Cushing syndrome, with symptoms of:

• Weight gain
• Muscle weakness
• High blood sugar (even diabetes)
• High blood pressure
• Increased body and facial hair
• Hump of fat on back of neck
• Skin changes like stretch marks (called striae)

Zollinger-Ellison syndrome

Carcinoid tumors can make a hormone called gastrin that signals the stomach to make acid. Too much gastrin can cause Zollinger-Ellison syndrome, in which the stomach makes too much acid. High acid levels can lead to irritation of the lining of the stomach and even stomach ulcers, which can cause pain, nausea, and loss of appetite.

Severe ulcers can start bleeding. If the bleeding is mild, it can lead to anemia (too few red blood cells), causing symptoms like feeling tired and being short of breath. If the bleeding is more severe, it can make stools black and tarry. Severe bleeding can itself be life threatening.

If the stomach acid reaches the small intestine, it can damage the intestinal lining and break down digestive enzymes before they have a chance to digest food. This can cause diarrhea and weight loss.

Although the exact number isn’t known, about 8,000 neuroendocrine tumors and cancers that start in the gastrointestinal tract (the stomach, intestine, appendix, colon, or rectum) are diagnosed each year in the United States. These tumors can also start in the lungs (see Lung Carcinoid Tumor for more information) and the pancreas, and a small number develop in other organs.

The number of carcinoid tumors diagnosed has been increasing for many years. The reason for this is unknown. Some think it may be a byproduct of doing more medical tests to look for something else and finding carcinoid tumors. Since many carcinoids never cause any symptoms, there are probably many people with carcinoid tumors that are never found. These tumors might only be seen during an autopsy when a person dies of something else, or when someone has surgery or imaging tests for an unrelated condition.

The most common location of gastrointestinal carcinoid tumors is the small intestine, often in the section near the appendix (called the ileum). Other common sites include the rectum, the colon (large intestine), the appendix, and the stomach.

The average age of people diagnosed with carcinoid tumors is in the early 60s. Carcinoid tumors are more common in African Americans than in whites, and are slightly more common in women than men.

A risk factor is anything that affects your chance of getting a disease such as cancer. For example, exposure to strong sunlight is a risk factor for skin cancer, while smoking is a risk factor for cancer of the lung and several other cancers.

But risk factors don’t tell us everything. Someone without any known risk factors can still develop cancer. And someone can have a risk factor, but still not get the disease. Only a few risk factors for gastrointestinal (GI) carcinoid tumors are known.

Genetic syndromes

Multiple endocrine neoplasia, type I

This is a rare condition caused by inherited defects in the gene MEN1. People with this syndrome have a very high risk of getting tumors of 3 glands: the pituitary, parathyroid, and pancreas. They also have an increased risk of carcinoid tumors. Some studies estimate that inherited mutations of the MEN1 gene are responsible for about 10% of carcinoid tumors. Most of these are gastric (stomach) carcinoids. Children have a 50/50 chance of inheriting this syndrome from an affected parent.

If your family is affected by the MEN1 syndrome, you might want to talk to your doctor about the pros and cons of getting tested for it. Although the gene that causes tumors in people with the MEN1 syndrome has been found, genetic testing for MEN1 is not widely available. Because the results of genetic testing are not always clear cut, it is important that the test is done along with genetic counseling to help you make sense of the results.

Neurofibromatosis type 1

This disease often runs in families and is characterized by many neurofibromas (benign tumors that form in nerves under the skin and in other parts of the body). It is caused by defects in the NF1 gene. Some people with this condition also develop neuroendocrine tumors of the small intestines.

Other genetic syndromes

Neuroendocrine tumors are also more common among people with tuberous sclerosis complex and von Hippel Lindau disease. Tuberous sclerosis complex can be caused by a defect in the TSC1 or TSC2 gene. People with this condition can also develop tumors of the heart, eyes, brain, lungs, and skin. People with von Hippel Lindau disease have an inherited tendency to develop blood vessel tumors of the brain, spinal cord, or retina, as well as kidney cancer. It is caused by changes in the VHL gene.

To find out more on being tested for genetic syndromes, see Genetic Testing: What You Need to Know.

Race and gender

Carcinoid tumors are more common among African Americans than whites. Outcomes are also not as good for African Americans. Researchers do not yet know why. Carcinoid tumors are also slightly more common in women than men.

Other stomach conditions

People with certain diseases that damage the stomach and reduce the amount of acid it makes have a greater risk of developing stomach carcinoid tumors, but their risk for carcinoid tumors of other organs is not affected.

Factors with uncertain or unproven effects

Smoking

Smoking may increase the risk of getting a carcinoid tumor of the small intestine, according to some research. But further studies are needed to confirm this.

Diet

The risk of developing GI carcinoid tumors does not appear to be increased or decreased by any specific foods.

Researchers have made great progress in understanding how certain changes in DNA can cause normal cells to become cancerous. DNA is the chemical in each cell that carries our genes, which control how our cells function. We look like our parents because they are the source of our DNA. But DNA affects more than the way we look.

Some genes control when our cells grow and divide. Certain genes that help cells grow, divide, and stay alive are called oncogenes. Genes that slow down cell division or cause cells to die at the right time are called tumor suppressor genes. Cancers can be caused by DNA changes that turn on oncogenes or turn off tumor suppressor genes.

Changes in 2 tumor suppressor genes are responsible for many inherited cases of neuroendocrine tumors and neuroendocrine cancers. Most inherited cases are due to changes in the MEN1 gene. A smaller number are caused by inherited changes in the NF1 gene.

Most neuroendocrine tumors and neuroendocrine cancers are caused by sporadic changes (mutations) in oncogenes or tumor suppressor genes. Mutations are called sporadic if they occur after a person is born, rather than having been inherited. The mutations that cause carcinoid tumors often affect the MEN1 gene, the same gene responsible for most familial neuroendocrine tumors and neuroendocrine cancers. But not much is known about exactly what causes these gene changes.

Doctors do know that carcinoid tumors start out very small and grow slowly. When patients have parts of their stomach or small intestine removed to treat other diseases, taking a close look under the microscope often shows small groups of neuroendocrine cells that look like tiny carcinoids. Researchers still do not know why some stay small but others grow large enough to cause symptoms.

Because carcinoid tumors usually grow and spread slowly, about half of all gastrointestinal carcinoid tumors are found in an early or localized stage, usually before they cause any problems.

Carcinoid tumors often are found incidentally (by accident). These tumors aren’t causing any symptoms but are found when tests are done for other diseases. They may also be found when parts of the gastrointestinal system are removed to treat other diseases.

For example, a person with stomach pain or bleeding may have a test called an upper endoscopy to look for an ulcer. In this test, the doctor looks at the stomach lining through a flexible lighted tube. During this test, the doctor may notice a small bump in the stomach wall that turns out to be a carcinoid tumor.

Sometimes during colorectal cancer screening, a routine sigmoidoscopy or colonoscopy (looking at the large bowel through a flexible lighted tube) will incidentally find a small carcinoid tumor.

Sometimes when the appendix is removed (to treat appendicitis or as part of a larger operation), a small carcinoid is found at the tip. This happens in about 1 of every 300 people who have appendix surgery done for other diseases. Most of these carcinoids were too small to have caused any symptoms.

If cancer keeps growing or comes back after one kind of treatment, it’s possible that another treatment plan might still cure the cancer, or at least shrink it enough to help you live longer and feel better. Clinical trials also might offer chances to try newer treatments that could be helpful. But when a person has tried many different treatments and the cancer is still growing, even newer treatments might no longer be helpful. If this happens, it’s important to weigh the possible limited benefits of a new treatment against the possible downsides, including treatment side effects. Everyone has their own way of looking at this.

This is likely to be the hardest part of your battle with cancer, when you have been through many treatments and nothing’s working anymore. Your doctor may offer you new options, but at some point you may need to consider that treatment is not likely to improve your health or change your outcome or survival.

If you want to continue to get treatment for as long as you can, you need to think about the odds of treatment having any benefit and how this compares to the possible risks and side effects. Your doctor can estimate how likely it is the cancer will respond to treatment you are considering. For instance, the doctor may say that more treatment might have about a 1 in 100 chance of working. Some people are still tempted to try this. But it is important to have realistic expectations if you do choose this plan.

Palliative care

No matter what you decide to do, you need to feel as good as you can. Make sure you are asking for and getting treatment for any symptoms you might have, such as nausea or pain. This type of treatment is called palliative care.

Palliative care helps relieve symptoms, but is not expected to cure the disease. It can be given along with cancer treatment, or can even be cancer treatment. The difference is that the main purpose of palliative care is to improve the quality of your life, or help you feel as good as you can for as long as you can. Sometimes this means using drugs to help with symptoms like pain or nausea. Sometimes, though, the treatments used to control your symptoms are the same as those used to treat cancer. For instance, radiation or chemotherapy might be used to help relieve pain caused by a large tumor. But this is not the same as treatment to try to cure the cancer.

Hospice care

At some point, you may benefit from hospice care. This is special care that treats the person rather than the disease; it focuses on quality rather than length of life. Most of the time, it is given at home. Your cancer may be causing problems that need to be managed, and hospice focuses on your comfort. You should know that while getting hospice care often means the end of treatments such as chemo and radiation, it doesn't mean you can't have treatment for the problems caused by your cancer or other health conditions. In hospice the focus of your care is on living life as fully as possible and feeling as well as you can at this difficult time. You can learn more by reading Hospice Care.

Staying hopeful is important, too. Your hope for a cure may not be as bright, but there is still hope for good times filled with happiness and meaning with family and friends. Pausing at this time in your cancer treatment gives you a chance to refocus on the most important things in your life. Now is the time to do some things you’ve always wanted to do and to stop doing the things you no longer want to do. Though the cancer may be beyond your control, there are still choices you can make.

You can learn more about the changes that occur when treatment stops working, and about planning ahead for yourself and your family, in Nearing the End of Life and Advance Directives.

For some people with gastrointestinal (GI) carcinoid tumor, treatment may remove or destroy the cancer. Completing treatment can be both stressful and exciting. You may be relieved to finish treatment, but find it hard not to worry about cancer coming back. (When cancer comes back after treatment, it is called a recurrence.) This is a very common concern in people who have had cancer.

It may take a while before your fears lessen. But it may help to know that many cancer survivors have learned to accept this uncertainty and are living full lives. Living With Uncertainty: The Fear of Cancer Recurrence gives more detailed information on this.

For other people, the cancer may never go away completely. These people may stay on drug therapy or get regular treatments with chemotherapy, radiation therapy, or other therapies to try to help keep the cancer in check. Learning to live with cancer that does not go away can be difficult and very stressful. It has its own type of uncertainty. Read When Cancer Doesn't Go Away for more about this.

Follow-up care

When treatment ends, your doctors will still want to watch you closely. It is very important to go to all of your follow-up appointments. During these visits, your doctors will probably ask questions about any problems you may have and examine you and order lab tests or x-rays and scans to look for signs of cancer or treatment side effects. Almost any cancer treatment can have side effects. Some may last for a few weeks to months, but others can last the rest of your life. This is the time for you to talk to your cancer care team about any changes or problems you notice and any questions or concerns you have.

Doctors often advise most people who have had their GI carcinoid tumors completely removed to return after several months for a complete physical exam and imaging tests to look for any signs of recurrence. Blood and or urine tests may be helpful for some patients. Further visits may be recommended every several months after that. For small rectal tumors, proctoscopy is often recommended 6 and 12 months after treatment. Small tumors of the appendix, when adequately treated, usually don't require close follow-up, as they are very unlikely to recur. Repeat upper endoscopy once or twice a year is usually recommended for patients with stomach carcinoids who have high gastrin levels. Your doctor may follow one of these schedules, but he or she might have reasons to recommend a different schedule as well.

It is very important to keep health insurance. Tests and doctor visits cost a lot, and even though no one wants to think about their cancer coming back, this could happen.

Should your cancer come back, When Your Cancer Comes Back: Cancer Recurrence can give you information on how to manage and cope with this phase of your treatment.

Seeing a new doctor

At some point after your treatment, you might see a new doctor who doesn’t know anything about your medical history. It’s important to be able to give your new doctor the details of your diagnosis and treatment. Gathering these details during and soon after treatment may be easier than trying to get them at some point in the future. Make sure you have the following information handy:

• A copy of your pathology report(s) from any biopsies or surgeries
• If you had surgery, a copy of your operative report(s)
• If you stayed in the hospital, a copy of the discharge summary that the doctor wrote when you were sent home
• If you were treated with radiation (including radiopharmaceuticals), a copy of your treatment summary
• Since some drugs can have long-term side effects, a list of your drugs, drug doses, and when you took them
• Copies of your imaging tests (which can often be stored digitally on a DVD, etc.)
• Contact information of the doctors who have treated your cancer

The doctor may want copies of this information for his records, but always keep copies for yourself.