Cancer starts when cells change and grow out of control. The changed or abnormal cells often grow to form a lump or mass called a tumor. Cancer cells can also grow into (invade) nearby areas. And they can spread to other parts of the body. This is called metastasis.

Carcinoid tumors are also called neuroendocrine tumors (NET). It's a rare type of cancer. Carcinoid tumors tend to grow slowly. Few people with these tumors have symptoms. So you may have a carcinoid tumor for many years and never know it.

Carcinoid tumors can grow anywhere in your body where there are hormone-producing (neuroendocrine) cells. Hormones are chemical messengers that travel through your blood. Most carcinoid tumors form in the digestive (gastrointestinal or GI) tract. This is likely because there are more neuroendocrine cells there than anywhere else in the body.

Here's where carcinoid tumors are most often found:

• Small intestine
• Appendix
• Rectum
• Colon
• Stomach
• Esophagus
• Pancreas
• Liver
• Lungs
• Bronchi
• Thymus

Carcinoid tumors differ a lot depending on how fast they grow, where they start, if they spread to other parts of the body, and if they make too much hormone.

Carcinoid tumors might be described based on how fast they grow:

• Slow-growing tumors. These are the most common type. They often stay small. They don't grow quickly or spread to other parts of the body.
• Faster-growing tumors. These tumors grow faster, grow larger, and spread.
• Hormone-secreting tumors. These functioning carcinoid tumors make hormones, including serotonin. The effect of serotonin and other hormones causes the symptoms known as carcinoid syndrome.

Another way to describe them is by where they start. For instance, it might be a GI neuroendocrine tumor (or GI NET) or a liver carcinoid tumor. The stage of the tumor defines if it has spread.

These tumors can also be grouped based on whether they make hormones:

• Functional tumors. These make hormones or other substances that cause symptoms.
• Nonfunctional tumors. These tumors are more common. They don't make hormones or don't make enough to cause symptoms.

All these things are found out while diagnosing carcinoid tumors.

A risk factor is anything that may increase your chance of having a disease. The exact cause of someone's cancer may not be known. But risk factors can make it more likely for a person to have cancer. Some risk factors may not be in your control. But others may be things you can change.

The risk factors for carcinoid tumor include:

• Family history. A family history of certain inherited genetic syndromes (those passed in families) can increase risk. Some of the syndromes linked to carcinoid tumors are multiple endocrine neoplasia type 1 (MEN1), von Hippel-Lindau syndrome, and neurofibromatosis type 1 (NF-1).
• Race and gender. Non-Hispanic black people tend to develop more GI carcinoid tumors than white people. Lung carcinoid tumors are more common in white people than people of any other ethnicity. Women tend to have a slightly higher risk than men.
• Other health problems. People with diseases that damage the stomach and reduce acid production have a greater risk of developing stomach carcinoid tumors. People with pernicious anemia also have a higher risk of developing stomach carcinoid tumors.
• Age. People of any age can develop carcinoid tumors. But they are rare in children. Commonly diagnosed between 50 and 70 years old.

Talk with your doctor about your risk factors for carcinoid tumor and what you can do about them.

In many cases, carcinoid tumors are nonfunctional and don't cause symptoms. (These tumors don't make hormones and other chemicals.) They might be found during a routine exam or when an exam or surgery is being done for another health issue.

In rare cases, a functional carcinoid tumor can cause a group of symptoms called carcinoid syndrome. This tends to happen after the tumor has spread most often to the liver. The symptoms may be triggered by exercise, stress, or certain foods and drinks, like alcohol (especially red wine), walnuts, pecans, bananas, tofu, and aged cheeses. These are common symptoms:

• Your face, neck, and upper body gets red (flushed)
• Intense itching
• Cramps
• Diarrhea
• Nausea or vomiting
• Asthma-like breathing problems (wheezing)
• Shortness of breath
• Fainting
• Fast heart rate (palpitations)
• Swelling around the eyes and increased tearing
• Blood pressure changes
• Right-sided valvular heart disease in some people

Symptoms of tumors that don't cause carcinoid syndrome depend on where the tumor is and may include:

• Belly (abdominal) pain or pressure
• Change in bowel habits
• Bloody bowel movements
• Chest pain
• Cough
• Wheezing
• Blood-tinged mucus (sputum)
• Nausea and vomiting
• No desire to eat
• Feeling tired all the time (fatigue)
• Weight loss
• A lump or tumor you can feel

Many of these may be caused by other health problems. Still, it's important to see a doctor if you have these symptoms. Only a doctor can tell if you have cancer.

It's hard to diagnose a small carcinoid tumor that's not causing carcinoid syndrome or other symptoms. These tumors are often found when doing surgery or an exam for another condition. For instance, some carcinoid tumors are found when the appendix is removed due to appendicitis.

These tests may be used to help diagnose carcinoid tumors:

• X-rays and scans. Chest X-ray, CT scan, PET scan, PET/CT scan, MRI scan and somatostatin receptor (SSTR) imaging are all useful in diagnosis. These imaging tests can show how big the tumor is and if it has spread.
• Biopsy. A surgical procedure may be needed to take out a tiny piece (sample) of tissue from the carcinoid tumor. This process is called a biopsy. The sample is sent to a lab and tested for cancer cells. A biopsy is important for diagnosis. It's the only way to know for sure that a tumor is cancer. Sometimes it's done by using a lighted, flexible scope to look inside your body. This is called endoscopy. If a tumor is found, a sample of tissue for biopsy can be taken out through the scope. It can also be done by putting a needle through your skin and into the tumor. A syringe is then used to pull out a tissue sample.
• Urine test. If you have a carcinoid tumor that's making too much serotonin hormone, it might show up as an acid in your urine called 5-HIAA (5-hydroxyindoleacetic acid).
• Blood test. A blood test might be done to check for increased levels of hormones or other substances, like serotonin, chromogranin A, and cortisol. The blood tests done depend on where the tumor is.

After diagnosis of a carcinoid tumor, you'll likely need more tests. These help your doctors learn more about the cancer. They can help show if the cancer has grown into nearby tissues or spread to other parts of your body. The test results help your doctors decide the best ways to treat the cancer.

The stage of a cancer tells how much cancer there is and how far it has spread in your body. The stage is one of the most important things to know when deciding how to treat cancer.

Stage groupings can have a value of 1 to 4. They're written as Roman numerals I (1), II (2), III (3), and IV (4). The higher the number, the more advanced the cancer is. Letters and numbers can be used after the Roman numeral to give more details.

Your doctor will talk with you about what your cancer stage is and what it means for your treatment. Make sure to ask questions so you understand your cancer stage and what it means.

The best treatment for small carcinoid tumors that have not spread is surgery. Surgery can cure these tumors. Once a tumor has spread or is too big to remove, other treatments may still work well. Here are some treatments that may be used:

• Partial surgery. If a tumor is too big to take it all out, surgery may be used to remove part of it so that other treatments may work better.
• Chemotherapy. Medicines that kill or slow the growth of carcinoid tumor cells may be given into your bloodstream or taken by mouth. Many times, several of these medicines are given together. If a carcinoid tumor has spread into your liver, chemotherapy may be injected right into your liver. Or small pellets may be injected into blood vessels in the liver to block blood flow to the tumor cells.
• Targeted therapy. These medicines act on certain genes or proteins that help cancer cells grow while limiting damage to healthy cells. They might be used to treat certain advanced carcinoid tumors.
• Immunotherapy. This medicine treatment helps your immune system better fight cancer.
• Somatostatin analogs. Octreotide and lanreotide are medicines that are given as a shot (injection). They help control the symptoms of a carcinoid tumor. They may also slow tumor growth.
• PRRT (peptide receptor radionuclide therapy). This treatment is with a radioactive medicine that binds to receptors on some kinds of carcinoid tumors. After binding to the cancer cells, the radiation damages them. This treatment might be used if the somatostatin analogs stop working.

Talk with your doctors about your treatment choices. Make a list of questions. Think about the benefits and possible side effects of each choice. Discuss your concerns with your doctor before making a decision.

You may also want to get a second opinion before starting treatment. It might help you learn about other treatment choices and can give you peace of mind about your treatment decisions.

Experts don't know how to prevent carcinoid tumors. None of the known risk factors can be controlled or changed.

You can help manage a carcinoid tumor by learning as much as you can about it and taking an active role in your treatment. Be sure to follow all your doctors' directions, take your medicines, and keep all your appointments. Tell your health care team about any side effects or other problems you're having. There are often ways to help. Here are some other tips:

• Try to follow a healthy, high-protein diet.
• Don't use alcohol or eat foods that trigger carcinoid symptoms.
• Reduce stress as much as you can.
• Ask your doctor about the medicines you take. Some, like decongestants, asthma inhalers, and antidepressants, may trigger or make carcinoid symptoms worse.
• Join a support group to learn more about carcinoid tumors and share your feelings with others.
• Try mind-body exercises, such as yoga or tai chi to help reduce anxiety and stress.
• Try other ways of managing emotional stress. Guided imagery, meditation, music therapy, and journaling might be helpful.
• Before appointments, write down your questions and bring them with you. For support during your appointments, bring a family member or close friend with you.

• A carcinoid tumor is a rare type of tumor that often grows slowly.
• Carcinoid tumors are cancer. But in many cases, they don't cause symptoms.
• In rare cases, a carcinoid tumor can cause a group of symptoms called carcinoid syndrome. This often happens after the tumor has spread.
• Carcinoid tumors can grow anywhere there are neuroendocrine cells (hormone-producing cells) in your body. They most commonly start in the digestive tract.
• The best treatment for small carcinoid tumors that have not spread is surgery.

Tips to help you get the most from a visit to your doctor:

• Know the reason for your visit and what you want to happen.
• Before your visit, write down questions you want answered.
• Bring someone with you to help you ask questions and remember what your doctor tells you.
• At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new instructions your doctor gives you.
• Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are.
• Ask if your condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if you do not take the medicine or have the test or procedure.
• If you have a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your doctor if you have questions, especially after office hours and on weekends and holidays.