What is Carcinoid Tumor? Symptoms, Diagnosis and Treatments

A Carcinoid tumor is a type of tumor that slowly grows inside the body.

The tumor is cancerous in nature.

These tumors are a subset of tumors, which usually begin in the lungs or the digestive system.

Most of these tumors usually do not have any signs and symptoms.

However, they can release hormones in the body that can lead to symptoms such as skin flushing and severe diarrhea.

If your doctor tells you that you have a carcinoid tumor, it can be a huge shock.

Depending on where it is located, you could experience a severe cough or belly pain.

Wherever the tumors show up, they will have an effect on hormone-making cells.

The tumor is part of an illness known as neuroendocrine tumors (NETs).

Although not common, the tumors can begin in the pancreas, the ovaries in women, or the testicles in men.

These tumors often grow quite slowly.

As a result, doctors are able to find them quite early.

Thus, they are quite easy to treat.

In order to get the best treatment, you will need to educate yourself as much as possible about the tumors.

Besides, you will need to involve family and friends so that you can get the kind of support you need.


The Neuroendocrine System

When carcinoid tumors manifest in the body, they will primarily attack the endocrine system.

That is why it is important to understand how the endocrine system works.

The endocrine system refers to cells inside the body that produce hormones.

Hormones are the chemical messengers that are released into the body.

They control various activities that take place inside the body.

The neuroendocrine system is made up of both hormone-producing cells and nerve cells.

The system exists throughout the body.

The cells of this system perform important functions such as airflow regulation, and the speed at which food moves through the digestive system.

Neuroendocrine cells are found throughout the body in organs such as the lungs and gastrointestinal (GI) tract, including the stomach and intestines.

Neuroendocrine cells perform specific functions, such as regulating air and blood flow through the lungs and controlling the speed at which food moves through the GI tract.


What are Neuroendocrine Tumors (NETs)?

Carcinoid tumors are part of the NETs family of tumors.

It is thus important to understand how they work.

The tumor starts when cells change and begin to grow uncontrollably.

Uncontrolled growth leads to the formation of a mass.

The tumor can be benign or cancerous in nature.

A cancerous tumor refers to a tumor that can grow to other organs in the body if it is not found and removed.

A benign tumor is one that grows but does not spread.

Such a tumor can be removed without leading to any harm.

NET tumors are masses that form in the part of the body responsible for hormone production.

Since the tumor develops from hormone-producing cells, the mass itself can produce hormones, which can lead to serious problems within the body.


Understanding Carcinoid Tumors

Carcinoid tumors are a specific type of NETs.

They begin in the different parts of the digestive system and the lungs with varying degrees.

Here is the frequency of where that is likely to be found:

  • Small intestine -39%
  • Rectum -15%
  • The bronchial system of lungs -10%
  • The appendix -7%
  • Colon -5%
  • The stomach -4%
  • Pancreas -2%
  • Liver -1%

They can occur in the ovaries, testicles, and other organs but only on rare occasions.

When they manifest in the neuroendocrine system, they produce excessive amounts of amines and neuropeptides, which are hormone-like substances.

The substances are not usually produced in huge amounts to cause symptoms sometimes.

Thus, tumors are often called slow-motion cancer.


Different Versions of Carcinoid Tumors

The tumors appear in two distinct forms: atypical and typical.

This difference usually results from how the tumors make and process a neurotransmitter called serotonin (5-HT).

Neurotransmitter controls depression and behavior.

  • Typical

This type of carcinoid tumor leads to the production of huge amounts of Chromogranin-A and Serotonin, which can be detected in the blood.

It also leads to the production of high amounts of 5-HIAA, which results from the breakdown of Serotonin.

It can easily be measured in urine.

  •  Atypical

People that contract these types of tumors usually have normal levels of chromogranin-A and serotonin in the blood.

Additionally, the 5-HIAA level in their urine is normal.

However, high amounts of 5-HTP, an amino acid can be found in the urine.

Additionally, there are usually high levels of serotonin in the urine.


Carcinoid Cancer History

The research into carcinoid cancer had rather modest beginnings.

It began with the description of cells scattered throughout the intestinal mucosa.

These cells were known to be reactive to chrome and silver salts.

The cells were noted for being functionally and morphologically different from other cells in the same mucosa.

One of the earliest scientists to study these cells was Nikolai Kultschitsky (1856-1925).

He wrote a paper while working at the University of Kharkov describing the unique characteristics of these cells.

Other investigators also confirmed his findings. Nikolai was one of the most influential scientists of his time in Russia.

However, he had to flee to Britain when the Bolshevik revolution began.

Lubarsch made the first detailed description of the tumors in 1888.

Two years later, Ranson reported the symptomology.

It was while describing a patient who was suffering from wheezing diarrhea, which appeared to be caused by a carcinoid that had metastasized to the liver.

Siegfried Oberndorfer, a German pathologist, was the first person in history to characterize them.

It was while at the University of Munich that he coined the word karzinoide, which means ‘carcinoma-like.’

He was describing the tumors, which behaved like benign tumors while they were, in fact, malignant in nature.

In 1914, Gosset and Masson were the first to recognize their relationship with the endocrine system.

The two used the silver impregnation technique, which led them to discover that the tumors originated from the enterochromaffin-like (ECL) and enterochromaffin (EC) cells within the digestive system.

Further research by Masson lead to carcinoid being characterized as argentaffin cell tumors in 1928.

In the 1950s, the fact that carcinoids were cancerous was confirmed.

It was after Erspamer and Asero did conclusive research and published their findings in 1952.

They conducted studies, which showed that these tumors had the ability to produce serotonin.

The WHO applied the term carcinoid to refer to tumors that originate from the endocrine system.

In 2000, the WHO redefined the term ‘carcinoid.’

However, the new definition has yet to receive global recognition.

According to the WHO definition, growths of the endocrine system are now categorized into neuroendocrine cancers and neuroendocrine tumors.

Tumors, according to the WHO are growths that appear benign in nature but could spread to other organs in the body.

Cancers are growths in the neuroendocrine system that look cancerous and can spread to the rest of the body.


Risk Factors

Risk factors are anything that influences the chances of you contracting a certain illness such as carcinoid tumors.

For instance, it is well known that exposure to the sun increases the chance of you getting skin cancer.

However, you should note that risk factors do not mean you will get cancer.

Someone who does not have these risk factors could still contract carcinoid cancer.

Here are some well-known risk factors for carcinoid tumors.


  • MEN Type 1

It is quite rare and results from an inherited defect in the gene called MEN 1.

If you have this defective gene, you have a high chance of getting tumors in these three glands: pancreas, parathyroid, and pituitary.

Additionally, there is a high chance of getting carcinoid tumors in the lungs and digestive tract.

Some of the data shows that the mutations in the inherited MEN 1 gene may be responsible for 10% of all cases of carcinoid tumors.

Most of the tumors caused by this defective gene appear in the stomach.

A child has a 50/50 chance of getting the gene from a parent that has it.

If your family has been known to have MEN 1 syndrome, it is important to discuss the pros and cons of getting tested for it with your doctor.

Since the results of gene testing are not always definitive, the test should be done in conjunction with genetic counseling.

That way, you are able to have better use for the results.

  • Neurofibromatosis type 1

The illness is genetic, and it runs in families.

It leads to numerous benign tumors forming in the nerves just below the skin and in other parts of the body.

The illness results from a defective NF 1 gene.

In some people, it could lead to the development of carcinoid tumors in the small intestines.

  • Other Genetic Risk Factors

Carcinoid tumors are prevalent in people that have the von Hippel-Lindau illness and tuberous sclerosis complex.

The tuberous sclerosis complex can result from a defective TSC1 or TSC2 gene.

If someone has this defective gene, they are at high risk of developing tumors in the eyes, brain, skin, and lungs.

Those who have the von Hippel-Lindau illness are at a high chance of contracting blood vessel tumors in the retina, spinal cord, brain, and kidneys.

A defective VHL gene causes von Hippel-Lindau syndrome.

Gender and Race

African Americans are at a higher risk of contracting this illness than whites.

Additionally, carcinoids tend to be more severe when they occur in African Americans.

Besides that, gender is another important risk factor.

Women are at a higher risk overall of contracting carcinoids than men.

Medical Conditions

If you have had a medical condition that causes the inflammation of the stomach walls, you are at a high risk of contracting this cancer.

It is especially so if the condition reduces the amount of acid that the stomach can produce.

However, stomach inflammation does not increase the risk of contracting tumors in other organs of the body.

Diabetes and Previous Cancer

People who have been dealing with diabetes have a high chance of contracting carcinoids.

It is especially so for women who have diabetes.

Besides that, if you had previously had cancer, such as cancer of the eye, you are at a high risk of contracting carcinoids.

Factors that are Unproven

These are factors where a clear link between the illness and the risk factor has not been proven.

However, they have raised suspicion as being possible causative factors:

These are factors where a clear link between the illness and the risk factor has not been proven.

However, they have raised suspicion as being possible causative factors:

  • Tobacco and Alcohol Use

Using tobacco, whether by smoking it or chewing it is thought to increase the chances of someone contracting carcinoids.

Additionally, alcohol is thought to increase the chances of contracting carcinoids in the pancreas.

However, research is still ongoing to confirm this suspicion.

  • Diet and Obesity

Studies have shown that people who do not take a balanced diet and are morbidly obese are at a high chance of contracting carcinoid tumors.

Hormone replacement therapy (HRT)

Although data is still inconclusive, it is thought that HRT doubles the risk of getting carcinoid tumors in the small bowel.

Further research is required to determine the kind of hormone replacement therapy and the duration of the therapy that increases the chances of getting cancer.



Screening means testing for a disease before any symptoms appear.

For a doctor to screen for cancer, they would need to have a test that does not lead to false positives and be reliable in detecting cancer.

Today, a definitive screening test for carcinoid cancer does not exist.

Among the reasons that there is no screening for carcinoid is that the risks are just too much compared to the benefits.

Besides that, it is quite rare, which means that only a small percentage of people would have it.

Consequently, the cost of screening for this cancer would be quite high.


How Carcinoids are Detected

Since carcinoids usually grow quite slowly, most of them are usually found before they lead to any major problems.

The tumors are usually found incidentally.

That means the tumors are not showing any symptoms but are found when carrying out tests when looking for other illnesses.

For instance, they could be found when a section of the gastrointestinal system is removed to treat another condition.

Another example is when someone complains about stomach pain, and upper endoscopy is done to look for an ulcer.

While the doctor is examining the stomach lining, he or she could come across a bump in the stomach wall that turns out to be a carcinoid tumor.

In other cases, the doctors could be screening for colorectal cancer.

The doctor will then come across a small bump that turns out to be a carcinoid tumor.

In other cases, during an operation to remove the appendix, a carcinoid tumor could be found at the tip.

It usually happens in about one in three hundred people that have appendix surgery.

The tumors are usually too small to have caused any problems.



In its early stages, carcinoid tumors do not have any signs or symptoms.

The symptoms only arise after cancer grows significantly huge or it metastasis to other organs in the body.

The symptoms of carcinoid tumors usually vary based on the affected organ.

If you do experience symptoms early on, they are usually vague.

For instance, you could experience abdominal discomfort.

If the tumors manifest in the small intestines, they can obstruct them or cause bleeding.

If they occur in the colon, they can also cause bleeding.

If they occur in the rectum, they can cause pain or rectal bleeding. The tumors usually grow quite slowly.

Consequently, the interval between the beginning of the symptoms and the diagnosis is usually quite long.

Carcinoid syndrome is one of the most common symptoms for people that have carcinoids.

It usually affects about 10% of people with tumors.

It is made up of a distinctive pattern of symptoms caused by the release of certain chemicals in high amounts within the bloodstream.

The symptoms can be made worse by consuming certain foods such as those that have high tyramine content.

They include blue cheese, alcohol, and chocolate.

The carcinoid syndrome usually manifests in people that have carcinoid tumors in the small intestines.

However, these symptoms do not appear until the cancer metastasis is in the liver.

The reason for this is that the liver can break down any excessive hormones that are produced by carcinoid tumors in the small intestines.

Carcinoids that occur in the lungs and other organs have also been known to cause carcinoid syndrome.


What to Expect from the Carcinoid Syndrome

Telangiectasias and Flushing

Most of the flushing occurs in the face.

However, the affected person can experience flushing in the trunk too.

The flushing is usually accompanied by a purplish skin appearance.

If you have carcinoid syndrome, you will not experience any sweating.

Rather, your skin will remain dry.

The flushing can last for a few minutes or can last for hours. In some cases, it can even become permanent.

The flushing is thought to result from the production of excessive amounts of histamine or tachykinin by the affected endocrine glands.

The Telangiectasias are collections of blood vessels that develop on the skin of people with carcinoids.

They mainly appear on the upper lips and nose and are thought to be caused by extreme vasodilation.


The diarrhea is usually watery and explosive in nature.

It affects about 78% of people who have carcinoid syndrome.

Diarrhea can occur a few times a day or as many as 30 times every day.

The symptom is thought to be caused by the excessive production of serotonin in the body.

Rapid Heartbeat

The rapid heartbeat is usually accompanied by a decrease in blood pressure.

The hypotension is thought to be caused by the dilation of the blood vessels.

The dilation of blood vessels may also be the reason why the skin appears flushed.

The symptoms are the result of bradykinin, which is used to dilate blood vessels.


It is also known as the closing off of airways.

The person affected will have symptoms similar to those with asthma.

The result is wheezing and problems with breathing.

However, the exact hormone that causes this symptom is not known.


Pellagra is the manifestation of dry skin.

It leads to a swollen tongue and cracked skin at the edges of the mouth.

Besides that, it can cause mental confusion.

Pellagra is normally associated with a deficiency in the production of vitamin B3.

In a normal person, the amino acid tryptophan is used to create vitamin B3.

However, in a person with carcinoids, most of the tryptophan is converted into serotonin that there is not enough of it to create vitamin B3.

The decrease in vitamin B3 can cause pellagra to occur.

Heart Failure on the Right Side

The excessive amount of serotonin in the body is thought to cause damage to the heart.

It results in the formation of lesions, which causes fibrosis of the heart valves.

The right side of the heart is usually affected when metastasis of the liver occurs.

The left side is unaffected since the serotonin is broken down in the lungs.


Diagnosis and Stages

When the symptoms are so overwhelming as to suggest that carcinoids may be present, a doctor will use different methods to find carcinoid tumors.

Additionally, he or she will do a test to establish whether the tumors have metastasized.

Besides that, a test helps the doctor to determine which treatment option will work best.

For most cancers, a biopsy is the only way a doctor can tell if the body has a tumor.

It entails taking a small section of the tissue and taking it to a lab.

If a biopsy cannot be done, other tests are used for the diagnosis.

When a doctor suspects that you have carcinoid tumors, he or she will request the medical and family history of the affected individual.

Additionally, he or she will perform a thorough physical exam.

These tests may also be performed when diagnosing carcinoid tumors.

  • Urine/Blood Test

A doctor will take samples of the blood and urine to check for the levels of hormones and other chemicals.

The urine test checks the level of 5-HIAA. Additionally, the levels of serotonin are also checked.

In some instances, the doctor can make a diagnosis based only on a urine test.

However, checking for chromogranin-A may be a better way to diagnose carcinoids.

The reason for this is that serotonin levels oscillate quite often.

  • Molecular Testing

The doctor could take a sample of your tumor to check for specific proteins, genes, and other r unique to carcinoid tumors.

The results of the test are what determine the treatment option.

  • Endoscopic Ultrasound

The ultrasound uses sound waves to make an image of the internal organs.

The procedure helps to show enlarged lymph nodes, which can help the doctor to determine the stage of cancer.

  • A Bone Scan

Bone scans use a radioactive substance to see inside bones.

When the substance is injected into the patient, it collects in areas that have cancer.

A Special camera is then used to show the areas that have cancer.

  • An X-Ray Scan

In some instances, an X-ray is used to show the internal structures of the body, including any tumors.

However, the tumor may not show up depending on its location and size.

Thus, other tests may be recommended.

  • Barium X-Ray Scan

In this scan, a person swallows a liquid that has some barium in it.

The barium coats the lining of the intestines, which makes it easy to see any anomalies.

When an anomaly is detected, an endoscopic biopsy is conducted to confirm the diagnosis.

Sometimes, the barium may be introduced into the digestive tract through the anus.

  •  CT Scan

A CT scan gives the viewer a 3D image of the insides.

The images are taken from different angles before a computer combines them to give a detailed view of the insides.

It helps to show any anomalies within the internal organs.

The patient may be given a special dye to swallow to give better contrast.

  • MRI

The MRI uses magnetic fields to produce images of the body.

The MRI scan requires the use of a special dye injected into the patient to give clear images.

  • Radionuclide Scanning

The test is done using a radioactive substance that attracted to carcinoid tumors.

A special camera is then used to show where the material has built up in the body.

It is a great way for identifying cancerous cells that have spread to organs of the body.

  • PET-CT Scan

The test entails the introduction of s small sugary substance in the body.

The cells that use the most energy in the body take up most of this substance.

Since cancer cells use up lots of energy, they take up more of the radioactive substance.

  • Biopsy

The procedure entails the removal of a small piece of tissue to be examined under a microscope.

A pathologist will then examine the tissue and give a diagnosis.

  • Endoscopy

The endoscopy lets the doctor see the lining of the upper digestive tract.

The person is usually sedated as the doctor performs the procedure.

Staging of the Cancer

The stage of the carcinoid tumor can help with a prognosis.

There is no internationally accepted staging system for carcinoid tumors.

Consequently, most doctors usually place them in three stages:

1) Localized

Cancer has not left the walls of the organ where it started.

For instance, it is still in the stomach, small intestines, or the rectum.

2) Regional

The cancerous tumors have reached the lymph nodes or they have grown through the walls of the organ where they started.

In most cases, it has reached nearby tissue such as ligaments, muscles, and fat cells.

3) Distant

Cancer has metastasized to distant organs that are not within the locality of where it began.

For instance, it may have reached the liver or the bones.


Treatments and Drugs

There exist various treatment options for carcinoids.

However, if you are not showing any symptoms, your doctor may decide to observe you.

  • Surgery

Surgery is usually recommended if you have a small tumor and are in good health.

Surgery may be done to get rid of the tumor. Alternatively, it may be conducted for relief.

If the tumor is obstructing your small intestines, surgery may be done to reduce the mass of cancer.

  • Interferon and Chemotherapy

Interferon is a substance used to inhibit the growth of tumors.

Interferon is used to slow down the growth of tumors in the body.

However, it does have some major side effects.

Chemotherapy is used alone or in combination with other treatment options.

The most common agents used are cyclophosphamide, 5-fluorouracil, doxorubicin, and streptozotocin.

The frequency of response to chemotherapy is only seen in 20% of cases and it may take months to see a response.

  • Radiation therapy

Radiation is used, especially when the tumors have metastasized in the spine.

The use of radiation is not effective in treating tumors within the liver.

  • Hepatic Artery Embolization

The surgery is usually done for people who cannot have surgery and the tumor has spread to the liver.

It entails cutting blood supply to the tumor so that the cells die of starvation.

The treatment may be done in combination with chemotherapy.

  • Somatostatin Analogues

The treatment is done using analogs such as lanreotide and octreotide.

These are proteins that slow down the production of the hormone production by the tumors, alleviating the symptoms.


Coping and Support

Cancer can place a lot of emotional, physical, and mental stress on the person undergoing the treatment.

For instance even after carcinoid cancer has been cured, you may have the mental anxiety of relapsing.

To deal with the physical symptoms, you will have to change your diet.

A dietician could give you important advice on how to relieve your symptoms.

You should also consider looking into how to relieve the symptoms of carcinoid cancer.

For instance, you can take vitamin supplements to relieve vitamin B3 deficiency.

You can also take special medication, which will alleviate constant diarrhea.

The family and friends of the person affected need to do everything they can to help alleviate the mental anguish.

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