Carcinoid syndrome 101

Carcinoid syndrome develops after a neuroendocrine tumor begins to grow within the body.

What are neuroendocrine tumors?

Neuroendocrine tumors (NETs) are rare generally slow-growing tumors arising from neuroendocrine cells. However, atypical tumors can be aggressive and grow more quickly.
Neuroendocrine cells are cells within the body that produce the hormones that control metabolism, digestion, and other important functions. They can originate in the gastrointestinal tract, lungs, appendix, thymus, and other organs.
These tumors can overproduce hormones such as serotonin, a chemical messenger within the body. When this happens, the result is frequently carcinoid syndrome.
Symptoms of carcinoid syndrome can include flushing, rapid heartbeat, and diarrhea.

Not everyone with NETs will develop carcinoid syndrome. However, up to 40 percent of people with carcinoid cancer will experience the symptoms of carcinoid syndrome.

Because neuroendocrine tumors are often symptomless, a symptom of carcinoid syndrome may be the first indication you have that something is wrong.

– Dr. Eugene A. Woltering, M.D. FACS, James D. Rives Professor of Surgery and Neurosciences, Section Chief of Surgical Endocrinology and the Director of Surgical Research at the Louisiana State University Health Sciences Center, New Orleans

“Carcinoidsyndrome.org is a superb site for both the NET newbie and the folks who have been around since Noah built the ark!!!”

– Dr. Eugene A. Woltering, M.D. FACS, James D. Rives Professor of Surgery and Neurosciences, Section Chief of Surgical Endocrinology and the Director of Surgical Research at the Louisiana State University Health Sciences Center, New Orleans

Neuroendocrine tumors

A rare tumor within the neuroendocrine system, typically found within the intestines and lungs.

These tumors can grow slowly, or spread quickly to other parts of the body, beyond the endocrine system.

Often people do not experience specific symptoms of neuroendocrine tumors, and instead a doctor detects the tumor by chance, during a routine physical examination.

Carcinoid cancer

A type of neuroendocrine tumor that can be classified as carcinoid cancer after it becomes malignant. Most often, the tumor has metastasized to the liver.

A rare and generally slow-growing form of cancer, it can begin in the intestines, stomach, lungs, colon, rectum, or appendix, or even more rarely in the ovaries and kidneys.

Carcinoid cancer is difficult to detect, and often becomes obvious only when late stage symptoms appear.

Carcinoid syndrome

Carcinoid syndrome occurs when a tumor in the neuroendocrine system is malignant and begins to overproduce certain chemicals, or hormones, causing specific symptoms.

One of the most important of these hormones is serotonin, which can have serious effects on the body.

Symptoms of carcinoid syndrome include dry, flushing, diarrhea, skin rash, rapid heart rate and shortness of breath.

Where neuroendocrine tumors may develop

Prevalence of carcinoid tumors versus other forms of neuroendocrine tumors

Signs & Symptoms

The symptoms of carcinoid syndrome can interfere with quality of life. These symptoms can be subtle or severe and may be different for each individual.

Diagnosis can be difficult to determine and can take time.

Many of the symptoms of carcinoid syndrome are common
symptoms of other medical conditions.

Common symptoms of carcinoid cancer and their occurrence

Carcinoid Heart Disease

Excess serotonin levels within the body can cause carcinoid heart disease, which is one of the most serious results of NETs and carcinoid syndrome.

Carcinoid heart disease is the development of plaque lesions on the lining of the heart, particularly on the right side of the heart, and the deformity of heart values causing their malfunction.

Carcinoid heart disease can develop in up to 50 percent of individuals with carcinoid syndrome.

Your doctor will determine if carcinoid heart disease has developed through regular monitoring of your symptoms and an examination of your heart, including a yearly echocardiogram (ECG) to look for heart value damage.

Symptoms of carcinoid heart disease:
  • Low blood pressure
  • Heart murmur
  • Fatigue
  • Shortness of breath
  • Development of fluid in the abdomen (ascites) and fluid in the feet (swelling or edema)
Experts Dr. Jerome Zacks and Dr. Patricia Pellikka provide an overview of the risk of carcinoid heart disease

Jerome S Zacks MD, FACC, FCCP
Center for Carcinoid and Neuroendocrine Tumors, Icahn Medical School at The Mount Sinai Medical Center, New York, NY

And Patricia A. Pellikka, MD, FACC, FAHA, FASE, Chair, Division of Cardiovascular Ultrasound, Mayo Clinic Rochester, MN