By Heather Jones 

 Medically reviewed by Doru Paul, MD

Carcinoid tumors, also called neuroendocrine tumors (NETs), are cancerous tumors that grow from the neuroendocrine cells, which are found in organs throughout the body and send and receive messages through hormones.¹²

Carcinoid tumors typically grow slowly and may not show symptoms for many years. In adults, these tumors are usually found in the digestive tract but may spread to other parts of the body. In children and young adults, they occur most frequently in the appendix or in the lungs and are less likely to spread than tumors in adults.

Read on to learn more about carcinoid tumors.

athima tongloom / Getty Images

Facts About Carcinoid Cancer

Some things to know about carcinoid tumors include:¹

• They grow from cells in the neuroendocrine system. These cells have commonalities with both nerve cells and endocrine cells (that make hormones).³

• They can be asymptomatic, with fewer than 10% of people who have them showing symptoms (depending on the location of the tumor).

• They are typically diagnosed between the ages of 55 and 65 but can be present for a while (sometimes years) before diagnosis because they grow so slowly.

• They are more common in Black people than White people, particularly Black men.

Key Statistics About Carcinoid Cancer

Fortunately, carcinoid cancer is quite rare. Some statistics include:

• Carcinoid tumors affect approximately 1 in 25,000 adults.²

• Carcinoid tumors are so rare in children and young adults that there is a lack of data to determine accurate statistics.

• The average age of diagnosis of digestive or lung carcinoid tumors is around age 60, but tumors are often present earlier.⁴

Types of Carcinoid Cancer

Carcinoid tumors can be categorized by how quickly they grow.¹

• Slow-growing tumors: The most common type. They usually stay small (under approximately an inch wide), and grow slowly and don't spread to other areas of the body.

• Faster-growing tumors: They may grow more quickly, grow larger, and spread to other areas.

They can also be categorized by their ability (or lack of) to make hormones.¹⁵

• Functional tumors: These make hormones (including serotonin) or other substances that cause symptoms (known as carcinoid syndrome).

• Nonfunctional tumors: These are more common. They don't make hormones at all (or not enough to cause symptoms).

Locations

Carcinoid tumors most often form in the gastrointestinal (digestive) tract, but can occur anywhere in the body that hormone-producing cells exist.¹

Areas carcinoid tumors are usually found include:

• Small intestine

• Appendix

• Rectum

• Lungs

• Colon

• Stomach

• Pancreas

• Liver

Rarely, they may occur in the:⁶⁷

• Gallbladder and bile ducts

• Ovaries

• Testicles

• Urinary bladder

• Prostate gland

• Breast

• Kidneys

• Brain

• Thymus gland

• Eye (very rare)

• Ear (very rare)

Carcinoid Cancer Symptoms

People with carcinoid cancer may or may not experience symptoms. If symptoms are present, they depend on where in the body the tumor(s) is located and can vary.²³

Appendix:

• Symptoms of appendicitis (such as pain)

Digestive Tract:

• Abdominal pain

• Diarrhea

• Nausea or vomiting

Duodenum (first part of the small intestine that connects to the stomach):

• Abdominal pain

• Diarrhea

• Constipation

• Change in stool color

• Nausea or vomiting

• Heartburn

• Jaundice (yellowing of the skin and whites of the eyes)

Jejunum (middle part of the small intestine) and Ileum (last part of the small intestine that connects to the colon):

• Abdominal pain

• Unexplained weight loss

• Fatigue/feeling very tired

• Bloating

• Diarrhea

• Nausea or vomiting

Colon:

• Abdominal pain

• Unexplained weight loss

Rectum:

• Blood in the stool

• Pain in the rectum

• Constipation

Lungs:¹

• Difficulty breathing

• Chest pain

• Wheezing 

• Cough

• Coughing up blood/blood-tinged sputum

• Symptoms that can be mistakenly diagnosed as pneumonia

Complications

Rarely, complications from carcinoid tumors can arise.

Carcinoid Syndrome

Carcinoid syndrome develops from tumors that produce hormones. It occurs in about 10% of people with a carcinoid tumor.²⁶

Symptoms of carcinoid syndrome include:

• Facial flushing (warmth and redness of the face, head, and upper chest)

• Nausea/vomiting

• Diarrhea

• Heart palpitations

• Fainting

• Wheezing

• Change in blood pressure (usually a decrease or low blood pressure)

• Change in weight (gain or loss)

• Malnutrition

• Dehydration

• Weakness

• Aching in muscles and joints

• Peptic ulcer

Symptoms can happen spontaneously or be triggered by factors such as:

• Exercise

• Some drinks, such as alcohol (particularly red wine)

• Stress

• Some foods, such as chocolate and certain cheeses

Carcinoid Heart Disease

Carcinoid heart disease (CHD) can occur in cases of advanced carcinoid tumors and carcinoid syndrome. CHD can lead to heart failure, but early recognition and surgical intervention may improve outcomes if completed before heart failure occurs.

CHD treatment involves a multidisciplinary approach and includes specialists with a broad range of experience.⁸

A heart valve replacement may be performed for some people with CHD.³

Cushing Syndrome

Some carcinoid tumors produce adrenocorticotropic hormone (ACTH). ACTH prompts the adrenal glands to produce too much of the steroid cortisol, which can result in Cushing syndrome.⁶⁹

Symptoms of Cushing syndrome may include:

• Flushed face

• High blood pressure

• Edema (swelling)

• Kidney stones

• Metabolic disturbances (such as high blood sugar or diabetes)

• Weight gain

• Bulge of fat on the back of the neck

• Muscle weakness

• Increased facial and body hair

• Skin changes, such as striae (stretch marks)

Risk Factors of Carcinoid Cancer

Some potential risk factors for carcinoid tumors include:²³

• Having (or having a family history of) multiple endocrine neoplasia type 1 (MEN1) syndrome or neurofibromatosis type 1 (NF1) syndrome

• Having certain conditions that affect stomach acid production, such as atrophic gastritis, pernicious anemia, or Zollinger-Ellison syndrome

• Smoking¹

• Being Black¹

Causes

The cause of carcinoid tumors is unknown. Researchers are investigating if the gene MEN1 may play a role in carcinoid tumors.²

Can Carcinoid Cancer Be Prevented?

Carcinoid tumors can't be prevented, but not smoking may lower your risk. Treating carcinoid tumors if they do arise may help prevent the symptoms of carcinoid syndrome.¹

Diagnosis

Carcinoid tumors that are small and do not cause symptoms are often found during an exam or surgery for another condition (such as appendix removal for appendicitis) rather than being evaluated specifically.¹

Tests that may be used in the diagnosis of a carcinoid tumor include:²³¹

• Imaging: Includes X-ray, computed tomography (CT) scan, magnetic resonance imaging (MRI), and positron emission tomography (PET) scan.

• OctreoScan: A special type of scan taken after the injection of a radioactive substance that is picked up by carcinoid tumor cells.

• MIBG scan: A very small amount of MIBG (radioactive material) is injected into a vein. As it travels through the bloodstream, carcinoid tumors take up the radioactive material, allowing them to be detected by a device that measures radiation.

• Physical exam and health history: During a general check-up body exam. A healthcare provider can take a history of current and past illnesses and treatments, as well as health habits.

• Biopsy: Involves examining a small sample of tissue from the carcinoid tumor under a microscope.

• Lab tests: Urine and/or blood tests look for signs of hormone level changes.

• Tumor marker test: Checking a sample of blood, urine, or tissue to measure the amounts of certain substances that could suggest the presence of cancer, such as chromogranin A.

• Scope procedures: An endoscope (thin instrument shaped like a tube with a light and lens) is inserted through the mouth and down into the stomach or small intestine to examine tissue and sometimes remove samples. A colonoscopy is a similar procedure, but the scope enters through the rectum. Ultrasound may be used with an endoscope to form pictures of body tissues (endosonography).

• Capsule endoscopy: The person swallows a capsule that contains a small camera in order to take pictures of the gastrointestinal tract.

Treatment

Treating carcinoid tumors depends on a variety of factors, such as:³

• The location of the tumor

• Whether it has spread to other areas of the body

• Whether it can be completely removed by surgery

• Whether it has come back after treatment

• Whether or not it has improved with treatment

Surgery

Surgery is typically the first-choice treatment for carcinoid cancer, with the goal of removing the entire tumor, if possible, and debulking (removing as much as possible) metastases (spread of cancer cells).⁶

The type of surgery used depends on the location of the tumor. Some types of surgeries include:³

• Endoscopic resection: Removes a small tumor in the gastrointestinal tract using an endoscope

• Local excision: Removes the tumor and a small amount of normal tissue around it

• Resection: Removes part or all of the organ in which cancer is present, sometimes including nearby lymph nodes

• Cryosurgery/cryotherapy: Destroys carcinoid tumor tissue through freezing using a specialized instrument

• Radiofrequency ablation: Using a special probe with tiny electrodes, high-energy radio waves (similar to microwaves) are released through the skin or through an incision to kill cancer cells

• Liver transplant: The cancerous liver is removed and replaced with a healthy liver from a donor

• Hepatic artery embolization: Blocks the hepatic artery (main blood vessel that brings blood into the liver) to help kill cancer cells growing in the liver

• Lobectomy, sleeve resection, or pneumonectomy: Removes all or parts of the lung⁶

Radiation

Radiation therapy uses types of radiation, such as high-energy X-rays, to kill cancer cells or prevent them from growing.³

Radiation therapy can be:

• External: A machine outside the body sends radiation toward the part of the body containing the cancer

• Internal: Needles, seeds, wires, or catheters containing radioactive substances are placed directly into or near the cancer

• Radiopharmaceutical: Radiation is administered using a drug that contains a radioactive substance, such as iodine (I-131)

Medications

Medications that may be used to treat carcinoid cancer include:¹⁰⁶³¹

Chemotherapy

• Uses drugs that kill cancer cells or stop the cells from dividing

• Can be administered by mouth, injected into a vein or muscle, or placed directly into the cerebrospinal fluid, an organ, or a body cavity

Hormone Therapy

• Helps stop extra hormones from being produced, control symptoms, and may block or reverse tumor growth

• The medications octreotide or lanreotide are injected under the skin or into the muscle

• May be combined with injection low-dose alpha interferon

Xermelo (Telotriastat Ethyl) Tablets

• In combination with somatostatin analog (SSA) therapy

• Approved for adults by the FDA in 2017 for the treatment of diarrhea associated with carcinoid syndrome that isn't adequately controlled by SSA therapy alone

Interferons

• Natural substances that activate the body's immune system and slow the growth of some tumor cells

• Interferon-alfa can help shrink or slow the growth of metastatic gastrointestinal carcinoid tumors and improve symptoms of carcinoid syndrome

• Given by injection

• May have flu-like side effects, which may be severe enough to hinder treatment

Treatment for Metastases 

Metastasis is when cancer cells spread from the primary tumor (where they began) to another part of the body via the lymph system or blood.³

The metastatic tumor is the same type as the primary tumor. For instance, if a carcinoid tumor in the gastrointestinal (GI) tract spreads to the liver, the tumor cells in the liver are GI carcinoid tumor cells, and it is classified as metastatic GI carcinoid tumor instead of liver cancer.

Metastatic carcinoid cancer treatments may include:²

• Somatostatin analogs: This may help stop the body from producing too many hormones. May slow the growth of the tumor when cancer cells have metastasized.

• Targeted therapy: Drugs that target certain genes or proteins are used to kill cancer cells.

If carcinoid cancer has spread to the liver, some treatments that may be used include:⁶¹

• Chemotherapy medicines: Injected into the liver

• Debulking of liver metastases: Done through procedures such as surgical excision, cryoablation, radiofrequency ablation, and hepatic artery catheterization

Treatment for Carcinoid Syndrome

Treatments for carcinoid syndrome may include:³

• Hormone therapy with a somatostatin analog

• Octreotide or lanreotide

• Interferon therapy

• Medications for specific symptoms

People with carcinoid syndrome may find it helpful to avoid things that may cause flushing or increasing breathing difficulty, such as:

• Alcohol

• Nuts

• Certain cheeses

• Foods with capsaicin (such as chili peppers)

Avoiding stressful situations and engaging in certain types of physical activity may also help with carcinoid syndrome.

Prognosis

The prognosis for carcinoid cancer depends on factors like:²³

• The location and size of the tumor

• Whether the cancer has spread

• If carcinoid syndrome and/or carcinoid heart disease is present

• Whether the tumor can be completely removed during surgery

It's important to discuss your prognosis with your healthcare provider, as they will be able to look at your specific situation.

Coping

First and foremost, follow all of the instructions provided to you by your healthcare provider about your treatment plan.

Some ways to help you manage while you go through treatment include:⁵¹

• Eat nutritious foods, including a high-protein diet

• Join a support group

• Practice mindfulness and relaxation techniques, such as meditation, guided imagery, journaling, yoga, or tai chi

• Learn about your condition, and write down any questions you have for your healthcare provider

• Consider bringing a family member or friend with you to your appointments for support

• Avoid things that trigger your symptoms

• Reduce stress as much as possible

Summary

Carcinoid tumors are slow-growing cancerous tumors found in areas of the body such as the GI tract and lungs. They may also spread to other parts of the body, such as the liver.

Many people with carcinoid tumors do not show symptoms unless complications, such as carcinoid syndrome, occur. Carcinoid tumors may be discovered during the diagnosis or treatment of another condition. Tools such as imaging, lab tests, and scope procedures may be used to make a diagnosis.

Surgery is the preferred treatment for carcinoid tumors, but other treatments, such as medication, radiation, and chemotherapy, may be used.

10 Sources

Johns Hopkins Medicine. Carcinoid tumor.

National Cancer Institute. Carcinoid tumor.

Dana-Farber Cancer Institute. Gastrointestinal carcinoid tumor.

MedlinePlus. Carcinoid tumors.

Cedars-Sinai. Carcinoid tumor.

National Organization for Rare Disorders. Carcinoid syndrome.

Carcinoid Cancer Foundation. A review of neuroendocrine cancer.

Grozinsky-Glasberg S, Grossman AB, Gross DJ. Carcinoid heart disease: from pathophysiology to treatment - ‘something in the way it moves’. Neuroendocrinology. 2015;101(4):263-273. doi:10.1159/000381930

American Cancer Society. Signs and symptoms of gastrointestinal carcinoid tumors.

American Cancer Society. Chemotherapy and other drugs for gastrointestinal carcinoid tumors.

By Heather Jones
Heather M. Jones is a freelance writer with a strong focus on health, parenting, disability, and feminism.