Carcinoid Syndrome
Description
Carcinoid syndrome is the set of symptoms that occur in people with carcinoid tumors. The symptoms are caused by the hormones and chemicals secreted by the carcinoid tumor and, in many cases, they are more severe than the effects caused by the growth of the tumor itself.
It was around the mid-19th century that carcinoid tumors were identified in Europe as a distinct type of tumor. The name "Carcinoid" was used for the first time in 1907 for classifying these tumors as an intermediate type between malignant (cancerous) and benign (non-cancerous) tumours.
Carcinoid tumors can be spread across much of the organism, but are usually found in the digestive system (50% of cases) or lungs (30% of cases). In children, carcinoid tumors usually develop in the appendix; After the appendix resection, cancer is usually cured.
Carcinoid tumors secrete excessive amounts of certain chemicals or hormones, which can cause reactions in the organism. The hormone serotonin is one of the chemical substances produced by carcinoid tumors. This hormone promotes dilation (enlargement) of blood vessels, blood coagulation and secretions as well as intestinal motility (causing diarrhea).
Carcinoid tumors are rare-about 1 to 2 cases for 100 000 people-and represent less than 1% of all cancers.
Causes
Carcinoid tumors are considered "slow cancers" because they evolve so slowly that people living with them can still live for many years, sometimes having a normal life span. Unfortunately, some carcinoid tumors secrete large amounts of hormones and other potent chemicals. This can cause a "carcinoid crisis" or carcinoid syndrome, which occurs infrequently at the beginning but more and more often thereafter.
Carcinoid syndrome often occurs without apparent cause, but it can be triggered by alcohol or physical or emotional stress.
Serotonin is the most commonly produced chemical, but not all carcinoid tumors produce the same range of hormones and chemical substances. It is not known which of the substances causes each of the symptoms associated with carcinoid syndrome.
Symptoms and Complications
Among the most pronounced and unpleasant symptoms of carcinoid syndrome are marked flushing puffs (face and bright red neck), abdominal pain and diarrhea (which may be important). Sometimes people may also have wheezing. Flushing puffs often occur after emotional stress, ingestion of certain foods or a hot beverage or alcohol consumption.
Less common symptoms include pulse acceleration, swelling of the face and the peri-ocular region, lower blood pressure and secondary weight loss to diarrhea or the inability of the intestines to absorb nutrients. Some people are also suffering from impotence and a decrease in libido (sexual impulse). A particular form of heart valve disease is sometimes observed, as well as related cardiac disorders.
Symptoms of carcinoid syndrome can usually be controlled using medications. Most complications arise from the carcinoid tumor, and the disease progresses differently in the presence of carcinoid syndrome than in the absence of it. However, the prognosis is much more favorable now thanks to new treatments, such as octreotide *.
Many years ago, the potent hormones released by tumors could produce deadly effects. Growth and spread of the tumor caused death in 25% of cases. Today, thanks to the effective combination of several treatments, including some medications, different surgeries, chemotherapy and other methods, the average life expectancy has improved.
Diagnosis
Most people who have a non-functional carcinoid tumor (which does not secrete anything) have no symptoms for many years. In most cases, it is abdominal pain or bowel movement that causes the person to consult a doctor. Once these symptoms are studied, the doctor can determine the cause.
Carcinoid syndrome can be easily diagnosed when all of its characteristic symptoms, or only one or two of them, are present. However, as the syndrome is rather rare, it may not be considered despite the presence of many symptoms.
If the doctor suspects Carcinoid's syndrome, the diagnosis can be quickly confirmed by a painless method of finding the presence of 5-HIAA in the urine. (This is the 5-hydroxy-indole-acetic acid-a product of serotonin degradation.) By knowing the amount of 5-HIAA in the urine over 24 hours, the doctor can determine the production of serotonin during this duration. The amount of 5-HIAA is almost always higher than normal in carcinoid syndrome.
This test very effectively identifies the active disease; It may however miss out on tumors that do not secrete or may give a false positive result because some foods and medications can also generate an elevation in the rate of urinary 5-HIAA.
For the determination of 5-HIAA, certain foods and medications should not be consumed for one or two days prior to the test to avoid distorting the analytical results. Among these we find:
Bananas;
Pineapple and juice
The Red Plum;
The lawyer;
Nuts;
THE kiwi;
Tomatoes
Cough Medications
Muscle relaxers;
acetaminophen;
Caffeine;
The fluorouracil;
Iodine Solutions
The phenacetin;
MAO inhibitors;
Isoniazid;
Drugs containing phenothiazine (prochlorperazine, chlorpromazine).
Sometimes the rate of 5-HIAA in the urine is not higher than normal but other markers in the blood, such as chromogranin-A and serotonin, are. In addition, the level of tryptophan in the blood is generally below normal.
The usual radiography and imaging techniques are then used to locate the tumor and determine how well it has invaded the tissues. These tests include a chest X-ray, a CT scan or a magnetic resonance imaging test, a barium enema, a barium meal and a hail transit (X-rays of the stomach and intestines). In some cases, endoscopy of the upper and lower gastrointestinal tract may prove useful; This examination allows to visualize the interior of the gastrointestinal tracts after the introduction of a flexible tube of fibre optics. However, these tests do not detect all cases of carcinoid tumors.
A very useful (but costly) diagnostic method is the OctreoScan scan, which detects about 85% of carcinoid tumors. A very small dose of a radioisotope that is specifically attracted by the tissues of carcinoid tumors, in which it concentrates, is injected beforehand. Carcinoid tumors are thus highlighted when the scintigraphe sweeps the entire body, allowing the tumor to be located. The radioisotope, which is harmless, is excreted by the organism within a few days.
A OctreoScan can be very useful to confirm the diagnosis and to locate the tumor in the rare cases of carcinoid syndrome where all the symptoms and all the chemical manifestations are known, but where the tests used to locate the tumor were Negative.
Treatment and prevention
Surgical removal of the tumor can completely and definitively cure the carcinoid syndrome. If it is impossible to completely excise the tumor tissue, removing important parts of it (surgical reduction) can alleviate the symptoms. Since most carcinoid tumors have very slow growth, volume reduction can relieve symptoms for a long time.
The injection of a substance called octreotide can reduce the manifestations of carcinoid syndrome and inhibit, or even reverse, tumor growth.
Techniques called cryoablation or radiofrequency ablation use probes that freeze or use radio waves to destroy metastases of the carcinoid tumor (the parts of the tumor that have spread) to the liver and cannot be excised Surgically.
Another method to reduce the volume of the tumor is to inject into the hepatic artery, which provides the tumor with its blood supply, a mixture of chemotherapy drugs and embolic products (to clog the artery). This prevents the supply of blood and oxygen to the tumor, while flooding it with drugs that destroy tumor tissues and inhibit its growth. As the drugs are concentrated in the tumor, the effects of chemotherapy are reinforced.
Radiotherapy may also be useful in the treatment of carcinoid tumors. To help control the disease, in some treatment centres, radioactive isotopes are injected into specific chemicals or drugs that accumulate easily in carcinoid tumors.
It is important to adopt a protein-rich diet if you are suffering from carcinoid syndrome. In addition, when diarrhea lowers the amount of certain vitamins (e.g. niacin) and mineral elements (potassium, magnesium, calcium, iron and salt), you should take the necessary supplements. Various medications can be prescribed to control diarrhea and facial redness episodes. Antihistamines and other medications are sometimes used to prevent carcinoid seizures.
People who have a carcinoid tumor should avoid alcohol and physical and emotional stress, as these are factors that can trigger a carcinoid crisis. For the same reason, adrenaline-related medications are to be avoided, including nasal decongestants and some inhaled asthmatics. Although some symptoms can be prevented using medications, the most effective preventive measure is to treat the carcinoid tumor itself.
* All medications have both a common name (generic) and a brand name. The brand is the name that a manufacturer chooses for its product (e.g., Tylenol ®). The generic name is the name of the medicine (e.g. acetaminophen). A drug may have several brand names, but it has only one generic name. This article lists the medications by their generic name. For information on a particular drug, see our drug database. For more information on brand names, consult your doctor or pharmacist.
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