Carcinoid syndrome is a group of symptoms associated with carcinoid tumors. These are tumors of the small intestine, colon, appendix, and bronchial tubes in the lungs.
Carcinoid syndrome is the pattern of symptoms sometimes seen in people with carcinoid tumors. These tumors are rare, and often slow growing. Most carcinoid tumors are found in the gastrointestinal tract and lungs.
Carcinoid syndrome occurs in very few people with carcinoid tumors, after the tumor has spread to the liver or lung.
These tumors release too much of the hormone serotonin, as well as several other chemicals. The hormones cause the blood vessels to open (dilate). This causes carcinoid syndrome.
The carcinoid syndrome is made up of four main symptoms including:
- Flushing (face, neck, or upper chest), such as widened blood vessels seen on the skin (telangiectasias)
- Difficulty breathing, such as wheezing
- Heart problems, such as leaking heart valves, slow heartbeat, low or high blood pressure
Symptoms are sometimes brought on by physical exertion, or eating or drinking things such as blue cheese, chocolate, or red wine.
Exams and Tests
Most of these tumors are found when tests or procedures are done for other reasons, such as during abdominal surgery.
If a physical exam is done, the health care provider may find signs of:
Tests that may be done include:
Surgery to remove the tumor is usually the first treatment. It can permanently cure the condition if the tumor is completely removed.
If the tumor has spread to the liver, treatment involves either of the following:
- Removing areas of liver that have tumor cells
- Sending (infusing) medicine directly into the liver to destroy the tumors
When the entire tumor can't be removed, removing large portions of the tumor ("debulking") can help relieve the symptoms.
Octreotide (Sandostatin) or lanreotide (Somatuline) injections are given to people with advanced carcinoid tumors that can't be removed with surgery.
People with carcinoid syndrome should avoid alcohol, large meals, and foods high in tyramine (aged cheeses, avocado, many processed foods), because they may trigger symptoms.
Some common medicines, like selective serotonin reuptake inhibitors (SSRIs), such as paroxetine (Paxil) and fluoxetine (Prozac), may make symptoms worse by increasing levels of serotonin. However, DO NOT stop taking these medicines unless your provider tells you to do so.
The outlook in people with carcinoid syndrome is sometimes different from the outlook in people who have carcinoid tumors without the syndrome.
Prognosis also depends on the site of tumor. In people with the syndrome, the tumor has usually spread to the liver. This lowers the survival rate. People with carcinoid syndrome are also more likely to have a separate cancer (second primary tumor) at the same time. Overall, the prognosis is usually excellent.
Complications of carcinoid syndrome may include:
- Increased risk of falls and injury (from low blood pressure)
- Bowel obstruction (from tumor)
- Gastrointestinal bleeding
- Heart valve failure
A fatal form of carcinoid syndrome, carcinoid crisis, may occur as a side effect of surgery, anesthesia or chemotherapy.
When to Contact a Medical Professional
Call for an appointment with your provider if you have symptoms of carcinoid syndrome.
Treating the tumor reduces the risk of carcinoid syndrome.
Flush syndrome; Argentaffinoma syndrome
Hande KR. Neuroendocrine tumors and the carcinoid syndrome. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 232.
National Cancer Institute website. Gastrointestinal carcinoid tumors treatment (Adult) (PDQ) - health professional version. www.cancer.gov/types/gi-carcinoid-tumors/hp/gi-carcinoid-treatment-pdq. Updated November 12, 2019. Accessed November 18, 2019.
Öberg K. Neuroendocrine gastrointestinal and lung tumors (carcinoid tumors), the carcinoid syndrome, and related disorders. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 25th ed. Philadelphia, PA: Elsevier; 2016:chap 43.
Review Date 7/26/2018
Updated by: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. 11-18-19: Editorial update.