A tumor is a growth of an abnormal mass of tissue in any part of the body. Tumors can differ in size and shape. It can be benign or malignant and can cause severe complications due to its uncontrollable growth. A common skin wart is an example of a benign tumor that stays in its original place and does not move to other parts of the body or invade nearby healthy tissue. But a cancerous tumor has the capacity to invade the normal tissue around it and spread throughout the body by using the lymphatic or circulatory systems.

What Is Carcinoid Tumor?

As neuroendocrine cells are present in all internal organs, carcinoid tumors can develop in any organ, including the liver, pancreas, lungs, bronchus, ovaries, thymus, and bile ducts. Hormones are a means through which neuroendocrine cells communicate with one another and with other parts of the body. Carcinoid tumor is slow-growing cancer. It is a type of neuroendocrine tumor and it is known to most commonly initiate in the digestive system of an individual. Therefore, the site of origin would include the colon, rectum, stomach, small intestine, and appendix. In most cases, treatment involves surgical options along with medications.

What Are the Types of Carcinoid Tumors?

Carcinoid tumors are categorized based on the presence of tumors in the primitive gut into:

Foregut carcinoid tumors (from the oral cavity to the initial part of the small intestine).
Midgut carcinoid tumors (from the mid-part of the small intestine to the initial part of the large intestine).
Hindgut carcinoid tumors (from the later part of the large intestine to the upper portion of the anus).

What Are the Causes of Carcinoid Tumors?

The actual cause of carcinoid tumors is not known. The accumulation of several cancer cells will result in the invasion of these cells into the surrounding healthy tissues. Therefore, several nerve functions are disrupted due to carcinoid tumors. Since there is the involvement of the neuroendocrine cells, the hormones that are produced by these cells, such as histamine, cortisol, serotonin, and insulin, are also disrupted.

What Is the Epidemiology of Carcinoid Tumors?

Medical reports help in studying the epidemiology of carcinoid tumors. It is identified as the most common tumor that could occur in the neuroendocrine tissues. Reports suggest that there has been an increase in the occurrence of carcinoid tumors every year. In some patients, it has been related to the increase in the usage of proton pump inhibitors such as Omeprazole, and Rabeprazole, worldwide. In adults, both men and women are known to be affected. However, the occurrence of such a tumor is very rare in children. The life expectancy of patients with carcinoid tumors is around five years. However, early detection of the condition might help improve the diagnosis.

What are the Signs and Symptoms of Carcinoid Tumor?

Some patients show no symptoms or signs at all. However, depending on where the tumor is, many categories of signs and symptoms exist.

A. Carcinoid Tumor - Digestive Tract:

Nausea and vomiting.
Diarrhea.
Redness or a feeling of warmth in the face and neck (flushing of the skin).
Abdominal pain.
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Rectal bleeding.

B. Carcinoid Tumor - Lungs:

Wheezing.
Chest pain.
Diarrhea.
Shortness of breath.
Redness in the neck and face.
Weight gain, specifically around the upper and midsection of the back.
Purple or pink marks on the skin will appear like stretch marks.

The symptoms might vary depending on the location of the carcinoid tumor. The carcinoid tumor in the liver will produce symptoms that are similar to the those caused by a carcinoid tumor in the digestive tract.

What Are the Complications of the Carcinoid Tumor?

The various complications that are associated with the carcinoid tumor are:

Malabsorption.
An increased thickness of the lining in the chambers of the heart, along with the blood vessels. In such conditions, surgical treatment is necessary.
Wheezing.
Asthma-like syndrome.
Pellagra- a condition characterized by dermatitis, mental disturbances, and diarrhea.
Carcinoid Syndrome - a condition in which there is diarrhea, breathlessness, and skin flushing.
Cushing Syndrome - a syndrome in which there are abnormally excessive levels of cortisol hormone.

How Is a Carcinoid Tumor Diagnosed?

The diagnosis of carcinoid tumors requires imaging techniques and blood tests.

A. Blood examination For:

5-hydroxy indole acetic acid [5-HIAA].
Histamine.
Serotonin.
Catecholamines.
Chromogranin-A.

B. Imaging Techniques and Studies:

Upper and lower gastrointestinal radiography with oral contrast agents.
Plain radiography.
Magnetic resonance imaging (MRI Scan).
Computed tomography (CT) scanning.
Technetium-99m bone scanning.
Ultrasound, including endoscopic ultrasound.
Angiography.
Scintigraphy with octreotide.
Positron emission tomography scanning.
Radionuclide imaging with the help of somatostatin analogs that are attached to the radioactive tracer.

C. Endoscopy:

Bronchoscopy: Bronchoscopy is the procedure in which the lungs are examined with a very thin tube containing light and a camera.
Esophagogastroscopy: Esophagogastroscopy is a procedure in which the stomach and the esophagus are examined to view the internal walls. An endoscope would be required for this purpose.
Gastroscopy: Gastroscopy is a procedure in which a flexible tube is used along with the camera to examine the stomach, esophagus, and duodenum.
Colonoscopy: In a colonoscopy, the intestine examination, especially the colon and the rectum, is done with the help of a camera located at the tip of the inserted tube. It is often a painful procedure and requires sedation.

What Are the Treatment Options for Carcinoid Tumors?

Treatment options include medication therapy and surgery. The medications that are given to the patients should be focused on destroying the cancer cells present in the body. It should also prevent the recurrence of cancer cells.

1. Medications - The medications that are recommended for carcinoid tumors are:

a. Octreotide and Lanreotide - These two medications are given in the form of injections. The side effects associated with these medications include bloating, abdominal pain, and diarrhea. Telotristat can be used to relieve the symptoms caused by carcinoid syndrome.

b. Chemotherapy - Surgery is not indicated for patients that have metastasis. In such cases, chemotherapy is the best available option. The drugs that are used for chemotherapy are called chemotherapeutic agents. The useful chemotherapeutic agents are listed below:

Doxorubicin.
Interferon alfa.
Alkylating agents.
Dacarbazine.
5-Fluorouracil.
Cisplatin.
Actinomycin D.
Streptozotocin.
Etoposide.

2. Surgery:

Surgery is planned according to the site of tumor involvement. Surgical excision or radiofrequency ablation is performed for the removal of the tumor.

Conclusion:

It is well recognized that a web of cellular signaling cascades regulates the growth, differentiation, phenotypic, and hormonal expression of carcinoid tumors. Several routes and specific compounds are now being investigated for their potential roles in the carcinogenesis of carcinoids. In any case, the prognosis and treatment of carcinoid disease depend on a variety of variables, such as tumor size, location, patient age, and histology, underscoring the necessity of customizing each therapy to the specific patient.

Frequently Asked Questions

1. Is a Carcinoid Tumor a Type of Cancer?

A carcinoid tumor is a rare type of slow-growing tumor that can occur in any body organ, including the liver, pancreas, lungs, thymus, and bile ducts. Though carcinoid tumors are malignant or cancerous, they have been named cancer in slow motion because the patient might have it but remain unaware of it for a prolonged period.

2. How Serious Is Carcinoid Cancer?

Carcinoid cancer can turn serious when exposed to trigger factors, including anesthetics, during the surgery. This condition is known as carcinoid crisis and can turn fatal. In addition, the patient usually experiences flushing, low blood pressure, confusion, and respiratory difficulties.

3. Is Carcinoid Tumor a Terminal One?

A carcinoid tumor produces symptoms that are not fatal at times. Sometimes, the tumor is incidentally diagnosed during a biopsy. People with large and malignant tumors can survive for years and have a good quality of life.

4. What Is the Survival Rate for Patients With Carcinoid Tumors?

Carcinoid tumor has been identified as the most common tumor that affects the neurological tissues. The survival rates according to the stages of the tumor are listed below:
- Localized - 97 %.
- Regional - 95 %.
- Distant - 66 %.

5. Can a Patient Live a Long Life After Being Diagnosed With a Carcinoid Tumor?

A carcinoid tumor is not deadly in itself but turns fatal when it damages the liver. A study reports that the median overall survival rate for patients diagnosed with carcinoid tumors is 41 to 59 months.

6. Are Carcinoid Tumors Curable?

Carcinoid tumors can be completely removed with surgery if detected early. However, removing the tumor altogether in an advanced stage becomes difficult. In addition, the treatments can only improve the patient’s life if the tumor has metastasized.

7. How Can a Patient Acquire Carcinoid Tumors?

The exact cause of the carcinoid tumor is still unknown. However, the accumulation of cancer cells due to genetic mutations disrupting the functions of the neurological tissues might be a cause. In addition, a study reports that people suffering from multiple endocrine neoplasia type 1 are more likely to develop carcinoid tumors.

8. Is It Necessary to Remove a Carcinoid Tumor?

It has been noted that carcinoid tumors grow at a slow rate and do not produce any symptoms. So, the complete removal of metastatic carcinoid tumors might not always be required. However, surgery can be done to remove all the visible portions of cancer.

9. What Are the Most Common Sites of Carcinoid Tumors?

A carcinoid tumor is a type of neuroendocrine tumor that usually initiates in the digestive system of humans. So, the site of origin and the most common tumor sites would be the small intestine and rectum. Some other common sites of carcinoid tumors include the colon, stomach, and appendix.

10. What Is the Best Treatment Option for the Removal of Carcinoid Tumors?

The treatment of carcinoid tumors depends upon their location, severity, and spread. Medications and surgery help manage carcinoid tumors. Surgery is usually indicated for carcinoid tumors because it helps remove the tumor. In addition, medications block the hormones released by the tumor and reduce the signs and symptoms.

11. What Foods Must a Patient Who Is Diagnosed With a Carcinoid Tumor Avoid?

The following foods must be avoided by patients suffering from carcinoid tumors:
- Coffee.
- Alcohol.
- Carbonated drinks.
- Raw vegetables.
- Vinegar.
- Cooked tomatoes.
- Smoked and salted fish.
- Sausages.
- Tofu and soy sauce.
- Yeast extracts.

12. Can a CT Scan Diagnose Carcinoid Tumors?

A CT (computed tomography) scan is commonly used to look at the chest and the abdomen to visualize the spread of the carcinoid tumor into the nearby lymph nodes or other organs like the liver. It can also be used to determine the exact location of insertion of the biopsy needle.

13. Are Carcinoid Tumors Benign?

Carcinoid tumors can be benign and are not always malignant or cancerous. For example, it has been noted that type 1 carcinoid tumors less than one centimeter are usually benign and account for about 75 % of all gastric carcinoids. In addition, though these tumors turn malignant, they usually grow slowly.

14. Can a Patient Have Pain Due to Carcinoid Tumors?

Carcinoid tumors are usually found incidentally during other diagnostic tests and procedures and do not cause pain. However, people suffering from rectal carcinoids might have abdominal pain and bleeding from the rectum.

15. Are Carcinoid Tumors Lung Cancers?

A carcinoid tumor is a neuroendocrine tumor, but lung carcinoids, also called lung carcinoid tumor, is a type of lung cancer. A lung carcinoid tumor usually occurs when the neuroendocrine cells in the lungs become cancerous.