Hormones are chemical messengers of the body that function in regulating a variety of body processes, such as metabolism, growth and mood. Specialized cells, called hormone-producing cells, are responsible for the production and release of hormones into the bloodstream. Neuroendocrine carcinoid tumors are a type of cancer that arises from a specific hormone-producing cell of the body.
Enterochromaffin Cells
Enterochromaffin cells are hormone-producing cells most commonly found in the lining of the digestive system, although also located elsewhere in the body. Serotonin is the primary hormone produce by these cells, accounting for 90 percent of the body's hormone production, according to The Medical Biochemistry Page. Carcinoid tumors most often arise from enterochromaffin cells, with the most common location being in the small intestines. These tumors have the ability to produce and release hormones into the body, negatively impacting normal bodily functions.
Causes and Risk Factors
Carcinoid tumors are rare in children and are more commonly seen in older adults. The tumors appear to occur sporadically, but individuals with a family history of multiple endocrine neoplasia type I syndrome are at an increased risk of carcinoid tumors. Smoking and conditions such as gastritis, pernicious anemia and Zollinger-Ellison syndrome are also risk factors. Although it is know that cancer arises from mutations in DNA, the exact cause of these mutations in carcinoid tumors is unknown, notes MayoClinic.com.
Symptoms
Due to the slow-growing nature of carcinoid tumors, symptoms often don't appear until later stages of the disease when the tumor is large or releasing secretory products into circulation. If present, symptoms are often grouped together and referred to as carcinoid syndrome, with the most common being diarrhea, skin flushing, and wheezing or breathing difficulties, according to a 2005 paper in The Oncologist. Symptoms vary depending on the chemicals released into the bloodstream, but may be triggered by alcohol, stress or strenuous exercise.
Classification
After the World Health Organization's classification of carcinoid tumors became outdated due to more advanced immunohistochemical testing techniques, a revised system was developed and published in a 1995 article in Virchows Archiv. This system grades tumors as benign, low-grade malignant or high-grade malignant, according to a 2005 paper in The Oncologist. The classification system is based on histopathology, size and location, hormone production and new blood vessel growth of the tumors.
Treatment
Several factors such as tumor grading and overall health of the individual must be considered when selecting a course of treatment for carcinoid tumors. If detected early, surgical removal of the tumor is the best option, but complete removal is often not possible if the tumor has had ample time to grow. Other therapies include radiofrequency ablation, killing tumors using heat or cold, and a type of immunotherapy called interferon alpha. Chemotherapy has not been shown to be useful for carcinoid tumors. Avoiding triggers of flushing and taking antidiarrheal medication can help alleviate some of the common symptoms, according to a 2005 article in The Oncologist.
