Introduction
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:
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Foregut carcinoid tumors (from the oral cavity to the initial part of the small intestine).
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Midgut carcinoid tumors (from the mid-part of the small intestine to the initial part of the large intestine).
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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:
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Diarrhea.
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Redness or a feeling of warmth in the face and neck (flushing of the skin).
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Abdominal pain.
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Rectal bleeding.
B. Carcinoid Tumor - Lungs:
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Wheezing.
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Diarrhea.
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Redness in the neck and face.
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Weight gain, specifically around the upper and midsection of the back.
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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:
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Malabsorption.
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An increased thickness of the lining in the chambers of the heart, along with the blood vessels. In such conditions, surgical treatment is necessary.
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Wheezing.
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Asthma-like syndrome.
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Pellagra- a condition characterized by dermatitis, mental disturbances, and diarrhea.
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Carcinoid Syndrome - a condition in which there is diarrhea, breathlessness, and skin flushing.
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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:
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5-hydroxy indole acetic acid [5-HIAA].
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Histamine.
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Serotonin.
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Catecholamines.
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Chromogranin-A.
B. Imaging Techniques and Studies:
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Upper and lower gastrointestinal radiography with oral contrast agents.
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Plain radiography.
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Magnetic resonance imaging (MRI Scan).
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Computed tomography (CT) scanning.
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Technetium-99m bone scanning.
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Ultrasound, including endoscopic ultrasound.
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Angiography.
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Scintigraphy with octreotide.
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Positron emission tomography scanning.
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Radionuclide imaging with the help of somatostatin analogs that are attached to the radioactive tracer.
C. Endoscopy:
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Bronchoscopy: Bronchoscopy is the procedure in which the lungs are examined with a very thin tube containing light and a camera.
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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.
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Gastroscopy: Gastroscopy is a procedure in which a flexible tube is used along with the camera to examine the stomach, esophagus, and duodenum.
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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:
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Doxorubicin.
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Interferon alfa.
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Alkylating agents.
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Dacarbazine.
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5-Fluorouracil.
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Cisplatin.
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Actinomycin D.
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Streptozotocin.
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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.