Carcinoid syndrome is a rare disease. The National Organization for Rare Disorders reports that just 27 carcinoid tumor cases per one million people in the U.S. are diagnosed each year. Of those, only 10 percent will develop into carcinoid syndrome.¹ People who have carcinoid syndrome may experience a variety of symptoms. It is important for people to seek treatment early to increase their chances of survival.

What Is Carcinoid Syndrome?

Carcinoid syndrome is a rare type of cancer that occurs when certain carcinoid tumors secrete chemicals into the bloodstream. The tumors grow from the neuroendocrine cells, a type of cell that is found throughout the body. According to Medscape, carcinoid tumors are most commonly found in the gastrointestinal tract. Only 10 percent of carcinoid tumors secrete the chemicals that cause malignant carcinoid syndrome.

Medscape also reports that carcinoid tumors may spread to the liver first. Once they spread to the liver, they can then metastasize throughout the body, and they frequently metastasize to the lungs.² In addition to cancer, carcinoid syndrome may cause complications, including carcinoid heart disease, bowel obstruction, and carcinoid crisis.

Symptoms

The symptoms of carcinoid syndrome will depend on which hormones are secreted from the carcinoid tumors. The Mayo Clinic reports that the most common symptoms include the following.

1. Skin flushing of the upper chest and face with episodes lasting from a few minutes to several hours
2. Purplish facial skin lesions on the nose and upper lip
3. Difficulty breathing with asthma-like symptoms
4. Severe diarrhea with abdominal cramping
5. Episodes of rapid heart beats³

People who experience these symptoms should see their doctors as soon as possible for a diagnosis.

Causes and Risk Factors

The Mayo Clinic reports that the causes of carcinoid tumors are unclear.³ Carcinoid syndrome itself is caused by a carcinoid tumor that secretes vasoactive hormones such as serotonin into the bloodstream. Most carcinoid tumors do not secrete the hormones that cause the syndrome to develop. Carcinoid tumors in the gastrointestinal tract that secrete hormones normally will have the hormones neutralized by the liver. However, if the original cells metastasize to the liver, the chemicals are no longer broken down and may then metastasize to the lungs, bones, skin, and other locations in the body.

The National Organization for Rare Disorders reports that possible risk factors for developing carcinoid tumors might include smoking and eating a poor diet, but the organization states that further research needs to be completed to confirm these risk factors.¹ One study that was published in the journal Neuroendocrinology in 2016 found the following risk factors for developing carcinoid tumors in the small intestine.

1. Family history of colorectal cancer
2. Family history of breast cancer
3. Smoking with heavy smoking carrying a greater risk
4. Drinking more than 21 units of alcohol per week⁴

The same study found that taking a low-dose aspirin each day could be a potential protective factor.

Treatments

There are several medical treatments that might be used to treat carcinoid syndrome.

First, doctors may use imaging to locate the primary carcinoid tumor and to see if it has spread. Then surgery may be recommended to remove the cancer or as much of it as possible. People might also receive injections of octreotide or lanreotide, which slow the growth of carcinoid tumors and block the cancerous cells from secreting chemicals. A drug called telotristat may be combined with the other injections to help to control diarrhea.

Patients may also receive injections of interferon alfa. This is a biological treatment that stimulates the immune system to fight against the cancer. It also helps to slow the growth of carcinoid tumors. Doctors may perform a procedure called hepatic embolization, which is a surgery on the arteries that supply liver carcinoid tumors to stop blood flow to them. Radiofrequency ablation may be used to kill the cancer cells in the liver by applying heat or cold through a needle inserted into the tumors. Finally, doctors might recommend that patients undergo chemotherapy to help to kill the cancer cells.

There are also several natural treatments that might be used to complement medical care. The Carcinoid Cancer Foundation reports that dietary changes might be helpful. The organization recommends that people increase their intake of protein, eat from five to 10 servings of fruits, vegetables, and whole grains each day, and keep fat relatively low at 25 to 30 percent of the diet. The CCF also recommends that people eat niacin-rich foods such as legumes and nuts.⁵

The Mayo Clinic recommends that people try to minimize stress and to exercise regularly.⁶ Since people should also try to avoid activities that could cause flushing, they might want to choose gentle exercises such as Tai chi or yoga. People might also benefit by attending support groups for people who have carcinoid syndrome if they can locate them in their areas.

Prognosis

The prognosis for people who are diagnosed with carcinoid syndrome is improving with advances in medical treatments. People who have inoperable carcinoid tumors can live for 10 to 15 years with modern treatments to slow the growth of the tumors.

According to Cancer Updates, Research, and Education, the FDA approved a new chemotherapy drug called Afinitor in 2016 for patients who have advanced and inoperable carcinoid cancer. That drug blocks a protein pathway to slow the growth of cancerous tumors. It is now being used in combination with an experimental drug called robciclib, which blocks two proteins that enable cancer cell growth. Another emerging treatment involves the use of Netspot treatment so that radiation can be used directly on cancerous tumors. A drug called Lutathera is in a phase 3 clinical trial and reportedly reduces the risk of death and disease progression by 79 percent.⁷

Advances in medicine show promise for helping people who have carcinoid syndrome to live longer and to enjoy better qualities of life. People who experience the common symptoms of carcinoid syndrome should see their doctors promptly. The doctors may determine whether they have carcinoid cancer or if their symptoms might be caused by another disease. People can then undergo the treatment regimens that are most appropriate for their diseases.