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gastrointestinal-carcinoid-tumors

Gastrointestinal Carcinoid Tumors

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What is a gastrointestinal carcinoid tumor?

The gastrointestinal system

The gastrointestinal (GI) system processes food for energy and rids the body of solid waste. It is also known as thedigestive system. 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.

           

The small intestine continues breaking down food and absorbs most of the nutrients. It is the longest section of the gastrointestinal (GI) tract, measuring more than 20 feet. The small intestine then joins the colon (large intestine). This is a wider, muscular tube about 5 feet long. The appendix is found near the junction of small intestine and colon. The colon absorbs water and mineral nutrients from the food matter and serves as a storage place for waste. The waste left after this process goes into the rectum. From there it passes out of the body through the anus as stool (feces).

The diffuse neuroendocrine system: Carcinoid tumors start from cells of the diffuse neuroendocrine system. This system consists of cells that are like nerve cells in certain ways and like hormone-making endocrine cells in other ways. These cells do not form an actual organ like the adrenal or thyroid glands. Instead, they are scattered throughout other organs like the esophagus, stomach, pancreas, intestines, and lungs. The digestive system is large and has more neuroendocrine cells than any other part of the body. This might be why carcinoid tumors most often start in the digestive system.

Neuroendocrine cells help control the release of digestive juices and how fast food moves in the GI tract. They may also help control the growth of other types of digestive system cells.

Neuroendocrine tumors: Like most cells in the body, GI tract neuroendocrine cells sometimes go through certain changes that cause them to grow too much and form tumors. These tumors are known as neuroendocrine tumors (NET) and neuroendocrine cancers. In the past, most abnormal growths of neuroendocrine cells were called carcinoids. But in 2000, the World Health Organization (WHO) reclassified carcinoids as neuroendocrine tumors and neuroendocrine cancers.

Neuroendocrine tumors are growths that look benign but that might possibly spread to other parts of the body. Neuroendocrine cancers are abnormal growths of neuroendocrine cells which can spread to other parts of the body.

Neuroendocrine cancers (also known as neuroendocrine carcinomas) can then be divided into groups based on the way the cells look under a microscope. A cancer with cells that do not look very abnormal is called well differentiated. These tumors tend to be less aggressive, meaning that they tend to grow and spread slowly. Well differentiated neuroendocrine cancers can look identical to benign neuroendocrine tumors when examined under the microscope. Sometimes the only way to know for certain that a mass is a neuroendocrine cancer (and not a benign tumor) is when it spreads to other organs or tissues. If the cells of a cancer look very abnormal, it is called poorly differentiated. Poorly differentiated cancers tend to be more aggressive, meaning that they grow and spread quickly.

Neuroendocrine tumors of the pancreas: Neuroendocrine tumors in the pancreas are known as islet cell carcinomas or pancreatic neuroendocrine tumors. Islet cell tumors are not the same as carcinoid tumors. They have a different prognosis (course of disease and outlook) and respond differently to treatment. These tumors are not discussed further in this document.

Carcinoid tumors: Carcinoid is the term used to describe well to moderately differentiated neuroendocrine tumors in the stomach, intestine, appendix, rectum, and lung. This document does not discuss carcinoid tumors that start in the lungs. 

Neuroendocrine tumors and cancers act like the cells they come from, often releasing certain hormone-like substances into the bloodstream. In most people with carcinoid tumors, the levels of these hormones are not high enough to cause symptoms. But in about 1 person out of 10 with carcinoid tumors, the tumor spreads and grows enough to release high amounts of these hormones. This can cause a set of symptoms known as the carcinoid syndrome. Some symptoms of the carcinoid syndrome include flushing (redness of the skin with a feeling of warmth), wheezing, diarrhea, and a fast heartbeat.

Other gastrointestinal tumors: Carcinoids and other neuroendocrine tumors are different from the more common tumors of the GI tract. Most GI tract tumors start from the glandular cells that produce mucus and make up the inner lining of the digestive system. When these tumors are benign, they are called adenomas. When these cells develop into cancer, the tumors are known asadenocarcinomas. These tumors differ quite a lot from carcinoid tumors in their symptoms, their outlook, and their treatment. For these reasons, it is important to know what type of tumor you have: a neuroendocrine tumor, a neuroendocrine cancer, an adenoma, an adenocarcinoma, some other type of tumor, or a non-cancerous condition. And it is important for patients to understand that neuroendocrine tumors and neuroendocrine cancers are not the same as other, more common types of GI tract tumors. 

In general, neuroendocrine tumors and neuroendocrine cancers grow slower than other cancers in the GI tract. But how they grow and whether or not they spread to other areas varies widely. This depends to some extent on which part of the body the tumor starts in.

What are the risk factors for gastrointestinal carcinoid tumors?

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 GI carcinoid tumors are known, such as:

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 gene NF1. 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 gene or the TSC2 gene. People with this condition may also develop tumors of the heart, eyes, brain, lungs, and skin. von Hippel Lindau disease is 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.

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 double the risk of getting a carcinoid tumor of the small intestine, according to a recent European study. But further research is needed to confirm this.

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

Do we know what causes gastrointestinal carcinoid tumors?

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 − the instructions for 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 have instructions for controlling when our cells grow and divide. Certain genes that make cells divide are called oncogenes. Others 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 mutations (defects) that turn on oncogenes or turn off tumor suppressor genes.

Mutations of 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 cases of neuroendocrine tumors and neuroendocrine cancers are caused by sporadic mutations of 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 that is responsible for most familial neuroendocrine tumors and neuroendocrine cancers. In many other types of cancer, researchers have shown that these acquired mutations are the result of cancer-causing chemicals in our environment, diet, or tobacco smoke. Relatively little is known, however, about factors that cause new mutations in genes that lead to neuroendocrine tumors and neuroendocrine cancers.

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 remain so small and others begin to grow and become large enough to cause symptoms.

Can gastrointestinal carcinoid tumors be prevented?

At this time, there is no known way to prevent gastrointestinal carcinoid tumors. Since smoking might increase the risk of carcinoid tumors of the small intestine, not starting or quitting smoking may reduce the risk for this disease.

Can gastrointestinal carcinoid tumors be found early?

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. In most of these cases, the carcinoid was too small to have caused any symptoms.

How are gastrointestinal carcinoid tumors diagnosed?

As mentioned in the last section, gastrointestinal (GI) carcinoids often do not cause any symptoms and may be found when looking for causes of other problems. But some do cause symptoms that may lead to their diagnosis.

Signs and symptoms of gastrointestinal carcinoid tumors

Most GI carcinoids grow slowly and produce vague symptoms that are more often caused by something else. 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.

The symptoms a person develops from a GI carcinoid tumor often depend on where it is located. People with tumors/cancers in their appendix often don’t have symptoms. If it is discovered, it is often when they have their appendix removed during an operation for some other problem. Sometimes, the tumor blocks the opening of the intestine and causes appendicitis. This leads to symptoms like nausea, vomiting, and abdominal (belly) pain.

If the tumor/cancer starts in the small intestine, it can sometimes kink or block the intestines, causing abdominal pain. This pain can be mild and last for a couple of years or more before the carcinoid tumor is found. A tumor usually needs to grow fairly large before it blocks (obstructs) the intestine. When that happens, patients have severe abdominal 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. These same problems can also occur with carcinoid tumors that start in the colon. Rectalcarcinoid tumors are often found during routine exams, even though they can cause pain and bleeding from the rectum.

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.

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 symptoms include:

Facial flushing (redness and warm feeling)

Severe diarrhea

Wheezing

Fast heartbeat

Many patients find that these symptoms are triggered by factors such as stress, heavy exercise, and drinking alcohol. 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 neuroendocrine tumors/cancers can 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 neuroendocrine 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's syndrome: Some neuroendocrine tumors/cancers may produce ACTH (adrenocorticotropic hormone), a substance that causes the adrenal glands to make too much cortisol. This can cause Cushing's syndrome, with symptoms of:

Weight gain

Muscle weakness

High blood sugar (even diabetes)

High blood pressure

Increased body and facial hair

Bump of fat on back of neck

Skin changes like stretch marks (called striae)

Medical history and physical exam: In taking a medical history, the doctor asks questions about the patient's 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/cancers 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/cancers 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-rays: These studies use a barium-containing solution that coats the lining of the esophagus, stomach, and intestines. The coating of barium helps show up 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 (also known as an upper GI series) is used to examine the lining of the esophagus, stomach, and the first part of the small intestine. The patient drinks a barium solution and then x-ray pictures are taken. Sometimes, a test called a small bowel follow-through is used to look for problems in the small intestine. For this procedure, which is a continuation of a barium swallow, x-rays are taken at regular intervals over the course of a few hours as the barium passes through the intestines.

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 more complete results than a small bowel follow-through, although placement of the tube can be uncomfortable, even when medicine is used to numb the throat.

Barium enema: This test (also known as a lower GI series) is used to look at the inner surface of the large intestine. 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 the colon, 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 colon or stomach with a narrow fiber optic scope.

Computed tomography scans: The computed tomography (CT) scan is an x-ray procedure that produces detailed cross-sectional images of your body. Instead of taking one picture, like a standard 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.

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

Before any pictures are taken, you could 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 may 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 ever had a reaction to any contrast material used for x-rays.

CT scans can help tell if your cancer has spread into lymph nodes or other organs such as your liver. They can also be used to guide a biopsy needle precisely into a suspected area of cancer spread. For a CT-guided needle biopsy, the patient remains on the CT scanning table, while a doctor moves a biopsy needle in the body toward the location of 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 thin cylinder of tissue about ½-inch long and less than 1/8-inch in diameter) is removed and looked at under a microscope.

Magnetic resonance imaging scans: Magnetic resonance imaging (MRI) scans use radio waves and strong magnets instead of x-rays. The energy from the radio waves is absorbed by the body and then released in a pattern formed by the type of tissue and by certain diseases. A computer translates the pattern into a detailed image of parts of the body. Like a CT scanner, this produces cross-sectional slices of the body. An MRI can produce slices that are parallel with the length of your body. As with a CT scan, a contrast material might be injected into a vein, but it is not needed as often.

MRI scans are a little more uncomfortable than CT scans. They take longer, often up to an hour. You have to be placed inside tube-like equipment, which is confining and can upset people with a fear of enclosed spaces (claustrophobia). If this is a problem for you, let your doctor know before the scan. Sometimes medicine given before the MRI can help. You may also be given the option of having the scan at an "open" MRI machine. Open MRIs are less confining, but the images are not always as clear as with a regular MRI. Also, MRI machines make a buzzing noise that some people might find disturbing. Some places will provide headphones with music to block this sound.

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 commonly used to look for carcinoid tumors. It uses a hormone-like substance called octreotide that has been bound to radioactive indium-111. Octreotide attaches to proteins on the carcinoid cells. A small amount of this substance is injected into a vein. It travels through the blood and is attracted to carcinoid tumors. 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 which 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 scans: A positron emission tomography (PET) scan is another imaging test that uses low levels of radioactivity to look for tumors. For most diseases, PET scans use a form of radiolabeled glucose (sugar) to find tumors. But when it is used to look for neuroendocrine tumors/cancers, PET uses a radioactive form of 5-hydroxytryptophan (5-HTP), a chemical that is taken up and used by carcinoid cells. A special camera can detect the radioactivity. Some doctors have found this type of PET scan to be more accurate than CT scans for detecting spread of disease. However, this special type of PET scan is not available in every hospital that has a PET scanner.

Endoscopy: These 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 masses in the lining of the digestive organs clearly. If abnormal areas are found, small pieces of tissue can be removed through the endoscope (biopsy). The tissue can be looked at under the microscope to find out if cancer is present and what kind of cancer it is.

Upper endoscopy: The endoscope is passed down through the mouth to show the esophagus, stomach, and first part of the small bowel. The procedure usually takes 15 to 30 minutes. If you are sedated for the procedure, you will need someone to take you home. This test is also known as esophogogastroduodenoscopy or EGD.

Most patients are given intravenous medicine to make them feel relaxed and sleepy during this procedure. An upper endoscopy may be done in a hospital outpatient department, in a clinic, or in a doctor's office.

Colonoscopy: A special endoscope known as a colonoscope is inserted through the anus up into the colon. Using the colonoscope, 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. This usually means drinking a large volume of a laxative solution the night before the exam (and then spending much of the night on the toilet). Sometimes an enema is also needed just before the procedure to make sure the bowels are empty.

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, in a clinic, or in a doctor's office. It usually takes 15 to 30 minutes, although it may take longer if a tumor is seen and/or a biopsy taken. Because medicine is given to make you sleepy for the procedure, you will need someone with you to take you home (not just a cab). This test is also called lower endoscopy.

Proctoscopy: Proctoscopy may be used to look for a rectal tumor. This involves using a shorter, rigid, hollow tube (a proctoscope), which is about 10 inches long and about 1 inch in diameter 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 very small camera. Like any other pill, the capsule goes through the stomach and into the small intestine. As it travels (usually over a period of 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 keeps being 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 detects the echoes that bounce off tissues of the digestive tract wall. A computer then translates the pattern of echoes into an image of the wall of the esophagus, stomach, intestine, or rectum. Putting the ultrasound probe on the end of an endoscope lets it get very close to the tumor. Because the probe is close to the area being studied, 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. Endoscopic ultrasound 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. This procedure is done after the patient is given drugs to make him or her sleepy, so you will need someone to take you home after this procedure.

Biopsy: Even if an imaging test finds a mass, it cannot tell if the mass is a carcinoid tumor, some other type of tumor or cancer, 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 gastrointestinal 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 was described in the section on CT scans.

Bleeding after a biopsy of a GI carcinoid cancer 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.

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 commonly used 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.

Eating foods that contain a lot of serotonin can raise 5-HIAA levels in the urine. Such foods include, bananas, plantains, kiwi, certain nuts, avocado, tomatoes, and eggplant. Medicines, including cough syrup and acetaminophen (Tylenol), can also affect the results. These substances should be avoided before urine and blood tests for carcinoids.

Other commonly used tests to look for carcinoids can include blood tests for chromogranin A (CgA), neuron-specific enolase (NSE), substance P, and gastrin. Drugs 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, and so patients need to be off these drugs when these levels are drawn. Depending on the tumor’s location and on the patient's symptoms, doctors 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.

How are gastrointestinal carcinoid tumors staged?

Staging — or determining the stage of disease — is the process of finding out if the tumor has spread, and if it has, how far. To help stage the tumor, doctors might use several types of imaging, endoscopy, or other tests described in the previous section, "How are gastrointestinal carcinoid tumors diagnosed?"

The stage of the tumor, along with the place it started, tells us about the prognosis (outlook) for someone with a gastrointestinal (GI) carcinoid tumor. These 2 factors also help the doctor decide what treatment to recommend.

Localized, regional, and distant stages

GI carcinoid tumors/cancers can start in several different locations, and until recently there had been no standard system for describing their spread. In the past, many doctors simply divided GI carcinoid tumors into 3 general stages: localized, regional spread, and distant spread. This approach was fairly easy to understand and could be useful when choosing among treatment options. It might not be possible to tell a benign tumor from a cancer when it is localized because the cells can look the same under the microscope. Any tumor that spreads, though, is a cancer (by definition).

Localized: The cancer has not spread beyond the wall of the organ it started in (for example, the stomach, intestine, or rectum).

Regional spread: The cancer has either spread to nearby lymph nodes or it has grown through the wall of the organ where it started to grow into nearby tissues such as fat, ligaments, and muscle (or both).

Distant spread: The cancer has spread to tissues or organs that are not near the organ where the cancer started (such as the liver, bones, or lungs).

The AJCC TNM system

Modern staging of GI carcinoid tumors/cancers uses a system created by the American Joint Committee on Cancer (AJCC) that is known as the TNM system. The TNM system for staging has 3 key pieces of information:

T describes the size of the primary tumor, measured in centimeters (cm), and whether the cancer has spread to organs next to the tumor.

N describes the extent of spread to nearby (regional) lymph nodes.

M indicates whether the cancer has metastasized (spread) to other organs of the body.

Numbers or letters appear after T, N, and M to provide more details about each of these factors:

The numbers 0 through 4 indicate increasing severity.

The letter X means "cannot be assessed" because the information is not available.

The letters "is" mean "carcinoma in situ," or the tumor is contained within the top layer of cells and has not yet reached deeper layers of tissue.

The T categories for GI carcinoid cancers differ depending on where the cancer starts, but the N and M categories are the same. Once the T, N, and M categories for a tumor are known, the information is combined to determine the overall stage. This process is known as stage grouping.

T categories for carcinoid tumors of the stomach

The T category describes how far down through the stomach layers the cancer has grown. The wall of the stomach is made of 5 layers.

The innermost layer is the mucosa. This is where stomach acid and digestive enzymes are made. The mucosa has 3 parts: epithelial cells which lie on top of a layer of connective tissue (the lamina propria), which is on top of a thin layer of muscle (the muscularis mucosa).

Under the mucosa is a supporting layer called the submucosa.

This is surrounded by the muscularis, a layer of muscle that moves and mixes the stomach contents.

The next 2 layers, the subserosa and the outermost serosa, act as wrapping layers for the stomach.

TX: Primary (main) tumor cannot be assessed due to incomplete information.

T0: The primary tumor cannot be found.

Tis: The tumor is less than 0.5 mm (about half the width of a grain of rice) and the cancer cells are found only in the top layer of cells of the stomach lining. This is also known as carcinoma in situ or severe dysplasia.

T1: The tumor has grown from the top layer of cells and into deeper layers, such as the lamina propria or the submucosa. The tumor is 1 cm (less than half of an inch) or less.

T2: Either:

OR

The tumor has grown into the lamina propria or submucosa (or both) and is greater than 1 cm.

The tumor has grown through the lamina propria and submucosa and into the main muscle layer of the stomach (called the muscularis propria).

T3: The tumor has grown through the muscularis propria and into the subserosa.

T4: The tumor has grown into the serosa (the outer layer of tissue covering the stomach, also called the visceral peritoneum) or into nearby organs or structures.

T categories for carcinoid tumors of the small intestine

T categories of small intestine cancer describe the extent of spread through the layers that form its wall.

The innermost layer of the intestine is known as the mucosa. It has 3 parts: the top layer of cells (called the epithelium), a thin layer of connective tissue (called the lamina propria), and a thin layer of muscle.

The other layers, from the inner to the outer, include, the fibrous tissue beneath the mucosa (submucosa).

A thick layer of muscle that contracts to force the contents of the intestines along (muscularis propria).

The thin outermost layers of connective tissue (subserosa and serosa) that cover the small intestine. The serosa is also known as the visceral peritoneum.

TX: Primary (main) tumor cannot be assessed.

T0: The primary tumor cannot be found.

T1: The tumor has grown from the top layer of cells and into deeper layers, such as the lamina propria or the submucosa. The tumor is 1 cm (less than half of an inch) or less.

T2: Either:

OR

The tumor has grown into the lamina propria or submucosa (or both) and is greater than 1 cm.

The tumor has grown through the lamina propria and submucosa and into the main muscle layer of the colon (called the muscularis propria).

T3: The tumor has grown through the muscularis propria and into the subserosa, the pancreas, and/or the retroperitoneum (the area in back of the abdomen).

T4: The tumor has grown into the serosa (the outer layer of tissue covering the intestine, also called the visceral peritoneum) or into nearby organs.

T categories for carcinoid tumors of the colon or rectum

T categories for carcinoid tumors of the colon and rectum cancer describe the extent of spread through the layers that form its wall. These layers are similar to those found in the wall of the small intestine (see above).

The innermost layer is known as the mucosa. It has 3 parts: the top layer of cells (called the epithelium), a thin layer of connective tissue (called the lamina propria), and a thin layer of muscle.

The other layers, from the inner to the outer, include, the fibrous tissue beneath the mucosa (submucosa).

A thick layer of muscle that contracts to force the contents of the intestines along (muscularis propria).

The thin outermost layers of connective tissue (subserosa and serosa) that cover the large intestine. The serosa is also known as the visceral peritoneum.

TX: Primary (main) tumor cannot be assessed due to incomplete information.

T0: The primary tumor cannot be found.

T1: The tumor has grown from the top layer of cells and into deeper layers, such as the lamina propria or the submucosa. The tumor is 2cm (about 4/5 of an inch) or less.

T1a: The tumor is less than 1 cm across (1 cm is less than half an inch).

T1b: The tumor is 1 to 2 cm across.

T2: Either:

OR

The tumor has grown into the lamina propria or submucosa (or both) and is greater than 2 cm.

The tumor has grown through the lamina propria and submucosa and into the main muscle layer of the colon (called the muscularis propria).

T3: The tumor has grown through the muscularis propria and into the subserosa or other tissue around the colon or rectum.

T4: The tumor has grown through the wall of the colon (or rectum) and into the serosa (also called peritoneum) and/or into nearby organs.

T categories for carcinoid tumors of the appendix

TX: Primary (main) tumor cannot be assessed.

T0: No signs of a primary tumor.

T1: The tumor is no more than 2 cm (2 cm is about 4/5 of an inch) across.

T1a: The tumor is no more than 1 cm across (1 cm is a little less than half an inch).

T1b: The tumor is larger than 1 cm but not larger than 2 cm across.

T2: Either:

OR

The tumor is larger than 2 cm but not larger than 4 cm.

The tumor has grown into the cecum (the first part of the large intestine).

T3: Either:

OR

The tumor is larger than 4 cm.

The tumor has grown into the ileum (the last part of the small intestine).

T4: The tumor has grown into nearby organs or tissues (such as the abdominal wall).

N categories for GI carcinoid tumors/cancers

NX: The cancer has spread to nearby (regional) lymph nodes and cannot be assessed.

N0: The cancer has not spread to nearby lymph nodes.

N1: The cancer has spread to nearby lymph nodes.

M categories for GI carcinoid tumors/cancers

M0: The cancer has not spread (metastasized) to distant organs or structures.

M1: The cancer has spread (metastasized) to distant organs or structures (such as the liver, lungs, bones, etc).

Stage groupings for carcinoid of the stomach

Stage 0: Tis, N0, M0: Carcinoma in situ: the tumor is less than 0.5 mm (and the cancer cells are found only in the top layer of cells of the stomach lining (Tis). The cancer has not spread to nearby lymph nodes (N0) or to distant sites (M0).

Stage I: T1, N0, M0: The tumor is 1 cm or less in size and has grown from the top layer of cells and into deeper layers, such as the lamina propria or the submucosa (T1). The cancer has not spread to nearby lymph nodes (N0) or to distant sites (M0).

Stage IIA: T2, N0, M0: Either the tumor has grown into the lamina propria or submucosa (or both) and is greater than 1 cm in size; OR the tumor has grown into the main muscle layer of the stomach (called the muscularis propria) (T2). The cancer has not spread to nearby lymph nodes (N0) or to distant sites (M0).

Stage IIB: T3, N0, M0: The tumor has grown through the muscularis propria and into the subserosa (T3). The cancer has not spread to nearby lymph nodes (N0) or to distant sites (M0).

Stage IIIA: T4, N0, M0: The tumor has grown into the outer layer of tissue covering the stomach (the serosa or visceral peritoneum) or into nearby organs or structures. The cancer has not spread to nearby lymph nodes (N0) or to distant sites (M0).

Stage IIIB: any T, N1, M0: The tumor can be any size and may or may not have grown into nearby structures (any T). It has spread to nearby lymph nodes (N1), but not to distant sites (M0).

Stage IV: any T, any N, M1: The tumor can be any size and may or may not have grown into nearby structures (any T). It may or may not have spread to nearby lymph nodes (any N). The cancer has spread to distant sites (most often the liver).

Stage groupings for carcinoid of the small intestine

Stage I: T1, N0, M0: The tumor is 1 cm or less and has grown from the top layer of cells and into deeper layers, such as the lamina propria or the submucosa (T1). The cancer has not spread to nearby lymph nodes (N0) or to distant sites (M0).

Stage IIA: T2, N0, M0: Either the tumor has grown into the lamina propria or submucosa (or both) and is greater than 1 cm; OR the tumor has grown into the main muscle layer of the intestine (called the muscularis propria) (T2). The cancer has not spread to nearby lymph nodes (N0) or to distant sites (M0).

Stage IIB: T3, N0, M0: The tumor has grown through the muscularis propria and into the subserosa (T3). The cancer has not spread to nearby lymph nodes (N0) or to distant sites (M0).

Stage IIIA: T4, N0, M0: The tumor has grown into the outer layer of tissue covering the intestine (the serosa or visceral peritoneum) or into nearby organs or structures. The cancer has not spread to nearby lymph nodes (N0) or to distant sites (M0).

Stage IIIB: any T, N1, M0: The tumor can be any size and may or may not have grown into nearby structures (any T). It has spread to nearby lymph nodes (N1), but not to distant sites (M0).

Stage IV: any T, any N, M1: The tumor can be any size and may or may not have grown into nearby structures (any T). It may or may not have spread to nearby lymph nodes (any N). The cancer has spread to distant sites (most often the liver).

Stage groupings for carcinoid of the colon and rectum

Stage I: T1, N0, M0: The tumor is 2 cm (about 4/5 of an inch) or less and has grown into the lamina propri

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