Carcinoid Tumors
Carcinoid tumors are small growths usually found in the intestinal tract. Carcinoid tumors are noncancerous ( benign ) or cancerous ( malignant ) growths that produce excessive amounts of hormonelike substances. Carcinoid tumors usually originate in hormone-producing cells that line the small intestine or other cells of the digestive tract. They can also occur in the pancreas, testes, ovaries, or lungs. Carcinoid tumors can produce an excess of hormonelike substances, such as serotonin, bradykinin, histamine, and prostaglandins. Excess levels of these substances can sometimes result in a diverse set of symptoms called carcinoid syndrome. When carcinoid tumors occur in the digestive tract or pancreas, the substances they produce are released into a blood vessel that flows directly to the liver ( portal vein ), where enzymes destroy them. Therefore, carcinoid tumors that originate in the digestive tract generally do not produce symptoms unless the tumors have spread to the liver. If the tumors have spread to the liver, the liver is unable to process the substances before they begin circulating throughout the body. Depending on which substances are being released by the tumors, the person will have the various symptoms of carcinoid syndrome. Carcinoid tumors of the lungs, testes, and ovaries also cause symptoms because the substances they produce bypass the liver and circulate widely in the bloodstream. Symptoms Most people with carcinoid tumors have symptoms similar to those of other intestinal tumors, mainly cramping pain and changes in bowel movements as a result of obstruction. Fewer than 10% of people with carcinoid tumors develop symptoms of carcinoid syndrome. Uncomfortable flushing, typically of the head and neck, is the most common and often the earliest symptom of carcinoid syndrome. Flushing, the result of blood vessel dilation, is often triggered by emotions, by eating, or by drinking alcohol or hot liquids. The flushing may be followed by periods when the skin is bluish ( cyanosis ). Excessive contraction of the intestines may result in abdominal cramping and diarrhea. The intestine may not be able to absorb nutrients properly, resulting in malnutrition and fatty, foul-smelling stools. Heart damage may occur, resulting in swelling of the feet and legs ( edema ). Wheezing and shortness of breath may result from obstructed airflow in the lungs. Some people with carcinoid syndrome lose interest in sex, and some men have erectile dysfunction ( impotence ). Diagnosis When symptoms lead a doctor to suspect a carcinoid tumor, the diagnosis can often be confirmed by measuring the amount of 5-hydroxyindoleacetic acid ( 5-HIAA )-one of the chemical by-products of serotonin-in the person's urine, which is collected over a 24-hour period. For at least 3 days before undergoing this test, the person refrains from eating foods that are rich in serotonin-bananas, tomatoes, plums, avocados, pineapples, eggplants, and walnuts. Certain drugs, including guaifenesinSome Trade Names ROBITUSSIN ( found in many cough syrups ), methocarbamol. Some Trade Names ROBAXIN ( a muscle relaxant ), and phenothiazines ( antipsychotics ), also interfere with test results. Different tests are used to locate carcinoid tumors. These tests include computed tomography ( CT ), magnetic resonance imaging ( MRI ), and arteriography. Sometimes exploratory surgery is needed to locate the tumor. Radionuclide scanning is another useful test. Most carcinoid tumors have receptors for the hormone somatostatin. Doctors can therefore inject a radioactive form of somatostatin into the blood and use radionuclide scanning to locate a carcinoid tumor and determine if it has spread. About 90% of tumors can be located using this technique. MRI or CT can be helpful in confirming whether the tumor has spread to the liver. Treatment When a carcinoid tumor is restricted to a specific area, such as the appendix, small intestine, rectum, or lungs, surgical removal may cure the disease. If the tumor has spread to the liver, surgery rarely cures the disease but may help relieve symptoms. The tumors grow so slowly that even people whose tumors have spread often survive for 10 to 15 years. Neither radiation therapy nor chemotherapy is effective in curing carcinoid tumors. However, combinations of certain chemotherapy drugs ( streptozocinSome Trade Names ZANOSAR with fluorouracilSome Trade Names EFUDEX ADRUCIL and sometimes doxorubicinSome Trade Names ADRIAMYCIN ) may relieve symptoms. A drug called octreotide. Some Trade Names SANDOSTATIN can also relieve symptoms, and tamoxifenSome Trade Names NOLVADEX , interferon-alpha, and eflornithineSome Trade Names VANIQA may reduce the tumor's growth. Phenothiazines, cimetidineSome Trade Names TAGAMET, and phentolamineSome Trade Names REGITINE are used to control flushing in people with carcinoid syndrome. PrednisoneSome Trade Names DELTASONE METICORTEN is sometimes given to people with carcinoid tumors of the lung who have episodes of severe flushing. Diarrhea may be controlled with codeine, tincture of opium, diphenoxylate, or cyproheptadineSome Trade Names PERIACTIN .
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